Hexa Extra Template 
You can edit header.tpl file (header.tpl.new can be renamed to header.tpl in overrides folder). Overrides folder will help with keeping customization during updates.
The navbar li item can be duplicated and customized for your needs.

<a href="/index.php?m=loginverifypin">Login verify</a>

Version 4.5.x you don't need to edit any template you can do of the Hexa Extra Menu

Flattern Extra Template

You can edit header.tpl file (header.tpl.new can be renamed to header.tpl in overrides folder). Overrides folder will help with keeping customization during updates.
The navbar li item can be 

<li><a href="index.php?m=clientnotifyn">Notification Settings</a></li>

Depending on what it's for you can add it as a link in:

/templates/template_name/includes/menu.tpl for the main menu or the following for the top right toolbar:

/templates/template_name/includes/toolbar.tpl

<li><a href="{$WEB_ROOT}/index.php?m=clientnotify">Notification Settings</a></li>

Version: 2.1.4 Released (12/01/2021)
Maintenance

Fixed Problem with WHMCS v8 gateways
Updated About Page
Updated Remove Support for PHP 5.6 to 7.0

Version: 2.1.3 Released (04/02/2018)
Maintenance

Update to work with WHMCS 7.5
Update to work with PHP 7.2 and Ioncube 10.1

Version: 2.1.2 Released (14/10/2017)
Maintenance

Updated Improve License Check
Updated WHMCS v7.3 support
Updated Make working with PHP 7 and Capsule
Updated WHMCSSERIVCES help page added

Version: 2.1.1 Released (10/10/2016)
Maintenance

Updated WHMCS v7 support

Version: 2.1.0 Released (25/10/2015)
Maintenance

Updated License Code

Version: 6.2.1 Released (01/03/2024)
Maintenance

Fixed support for ionCube Loader v13
Updated Licence System with Cloudflare
Updated Improve ionCube Loader

Version: 6.2.0 Released (11/28/2023)
Minor

Added A note on the Services page
Added Top bar to the top of the page
Added Support PHP 8.2
Fixed PHP 8.1
Updated Remove Support for WHMCS V8.4.x to 8.5.x

Version: 6.1.1 Released (12/04/2022)
Maintenance

Added Italian Language
Fixed issue with display popup in special pages
Fixed support for ionCube Loader v12 and PHP 8.1
Updated Remove Support for PHP 7.1 to 7.3
Updated Remove Support for WHMCS V8.1.x to 8.3.x

Version: 6.1.0 Released (12/29/2021)
Minor

Added Add fund page banner
Updated New WHMCSServices menu to work with WHMCS 8. x
Fixed Problem with PHP 7. x
Fixed Problem with popup predefined styles
Fixed Button Not Functioning

Version: 6.0.0 Released (09/22/2020)
Stable

Added Admin User with many updates and improvements
Added New predefined popup list
Added New template notification
Added Archive notification feature
Added Start at notification
Added Preview popup
Added index.php to all directories
Fixed Admin issues
Fixed htaccess rewrite URL
Fixed breaking the third-party WHMCS theme called Control (impressivethemes)
Updated Module tables renewed
Updated Remove v4 Admin theme from distribution
Updated Remove Support for PHP 5.6 to 7.0

Version: 5.0.7 Released (12/03/2018)
Maintenance

Fixed blank HTML paragraph

Version: 5.0.6 Released (08/03/2018)
Maintenance

Fixed third-party WHMCS theme called  SwiftModders Themes
Fixed Expiry Date

Version: 5.0.5 Released (07/26/2018)
Maintenance

Fixed Correct language in about page
Fixed Product group notification
Updated New WHMCSServices menu to work with WHMCS 7.6
Updated Show alert when template missing

Version: 5.0.4 Released (06/04/2018)
Maintenance

Fixed PHP 7.1 and PHP 7.2
Fixed to work with WHMCS 7.5

Version: 5.0.3 Released (06/11/2017)
Maintenance

Fixed an improvement running in WHMCS 7.4
Fixed links added to the top notification

Version: 5.0.2 Released (15/10/2017)
Maintenance

Fixed Default WHMCS hook conflict problem
Updated WHMCS SERVICES help page added

Version: 5.0.1 Released (13/10/2017)
Maintenance

Fixed Upgrade from the 4.0 version problem
Fixed None multi-language problem

Version: 5.0.0 Released (10/10/2017)
Stable

Added Top notification
Added Popup notification
Added Allowing the client to show notifications with shortcodes
Added Set of custom colors and font added
Added Multi-languages
Added Custom CSS
Added Show notification to a product clients
Added Show notification to an Addon clients
Added Auto adding codes to the template file
Fixed Product Group

Version: 4.1.0 Released (30/01/2017)
Updated

Updated Improve the license call

Version: 4.0.0 Released (22/12/2016)
Stable

Fixed Middle notification does not show
Updated CKEditor Update
Updated New and faster licensing system implemented
Updated V7 Comparability
Updated Duplicate Button
Added Full recode of module helping the performance

Version: 3.1.0 Released (22/10/2015)
Maintenance

Updated License Code

Global settings:

 

Fixed small bug on WS Affiliates Plus 1.0.2 for WHMCS Now Available - https://www.whmcsservices.com/affiliatesplus.php

Changelog
1.0.2

Fixed Send email problem when order not accepted problem resolved

If you are looking for someone to develop a Custom WHMCS, Blesta, WISECP Application for you, whether it's for you to sell to other people; for your company to use; or whatever the reason, feel free to contact us for a quote. We will discuss the project with you and come up with a very reasonable and cost-effective price.

Our programming is primarily designed with the view to offer quality web solutions at affordable rates. Small enterprises can greatly benefit by getting affordable web solutions of high standards.

For more information, you can go to https://www.whmcsservices.com/customworks.php.

Chat with us through live support or send in a ticket if you would like more information.

Thanks, and we at WHMCS Services look forward to being the provider of your company's peace of mind...and your Programmer solution!

If you have any questions about our services, please chat with us at http://www.whmcsservices.com

WHMCS Services is pleased to announce our affiliate program, here's a quick outline of key features:

PROGRAM FEATURES & BENEFITS
Commission paid on recurring revenue, not just one-time payout!
No need to provide support, WHMCS Services supports end-user (s) directly
No risk of credit card charge backs and/or loss of payment processing accounts
No loss of payment processing fees (2-5% typical savings)
You'll earn $3.00 just for doing it! It can't get much better than that.
Direct Link Tracking: From your secure site, link directly to WHMCS Services without using your referral URL for increased conversions.

COMMISSION RATES
Source Code Version - 35%
License Version - 20%

AFFILIATE PROGRAM TERMS
$50.00 minimum withdrawal limit
60-day commission payout delay (due to high industry fraud)
Resale discounted products are not eligible for commission
WHMCS Services reserves right to change terms/rates on new referrals at any time
You must not try to process self-referrals as we could block you from the affiliate program.
Setup fees (the few that there are...) are currently not eligible for commission
Custom Developer are currently not eligible for commission
Add-ons ordered after initial order placements are currently eligible for commission
We reserve the rights to reverse commissions that do not have referral URLs.
I will add 25% commission on your account all you need to do is email us in the subject WS Affiliates

Visit our affiliate page for more details!

High quality affordable WHMCS Modules from whmcsservices.com - Serving you for over 15 years.

Thank you for taking the time to read this thread.

New York – 26/06/2017 –  WHMCS Services has bought all RivaWeb's WHMCS Modules and clients. WHMCS Services will now carry on offering and supporting all these WHMCS Modules. WHMCS Services will now deliver top-notch products and services to all clients. WHMCS Services is strong, fully-fledged, support, billing, and customer management solutions company that will always deliver for customers who want reliable and excellent services.

RivaWeb was offering a variety of WHMCS Modules to its huge customer-base and it is for this reason that WHMCS Services found it worthwhile to purchase WHMCS Modules and clients from RivaWeb. With the purchase of WHMCS Modules and Clients from RivaWeb, WHMCS Services will provide software solutions for the clients who were customers of RivaWeb. This purchase will expand WHMCS Services customer-base and improve features in different packages. 

The additional WHMCS Modules from RivaWeb will expand the scope of WHMCS services and provide the clients with a wide variety to choose from. WHMCS Services will continue to provide automatic billing, customer sign-up, provisioning, and termination among others. Client support will continue to be integrated with support tickets and a comprehensive knowledge base. WHMCS Services will also continue to offer a dedicated developer, and support for email, and much more. 

About WHMCS Services
WHMCS Services is based out of New York City, New York; WHMCS Services develops and deploys innovative software solutions for various web hosting providers throughout the industry. Our software programs are developed for both Internet users and Web hosting providers. Some of the most popular products in our portfolio are WHMCS Modules. We also offer WHMCS integration, SSL Certificates, custom works, Web design, affiliate marketing, and advertisement. We are a one-stop-shop for all your software needs. You can reach us at http://www.whmcsservices.com. WHMCS Services was founded in 2004. 

You can find them on the web at: http://www.whmcsservices.com and on Twitter at: https://twitter.com/WHMCSServices.

New York – 01/10/2016 - WHMCS Services (WS) is a software company established since 2004.  WS is well-known and highly regarded in the web hosting industry space for their great software products they have developed and are used by many companies. WS has been has been around for 12 years and is continuing to grow and offer great products to fill the demands of customers/clients.
 
Today, WHMCS Services (WS) has announced that they have purchased WHMCSapps.com. WHMCS Services will continue to offer all of the services that WHMCSApps previously offered, but will now execute and deliver same services under the name of WHMCS Services.
 
WHMCS Apps' goal was to continually innovate and provide advanced, quality products and solutions; complemented by responsive and knowledgeable customer service personnel ready to provide timely support. They also aimed to provide value for the money by offering packaged deals to the price conscious consumer. All these values and offers will be continued by WS.
 
Over the past months, WHMCSApps.com has been very successful and has grown their customer-base by significant numbers, which is why WHMCS Services felt it was necessary and important to purchase the company. With this acquisition, WS will now enhance its own portfolio and make available ALL products to even more customers and companies throughout the industry.
 
The company, WHMCS Services, and its new WHMCSApps.com services will continue its fantastic B2C relationships to meet the needs of its customers and offer great products as it has being doing for the past 12+ years.  And to enhance the B2C relationship even further, WHMCS Services' will employ their own customer service reps and employees specifically for WHMCSServices.com to ensure that the customers of WHMCS SApps are taken care of to the best of their abilities.
 
With the purchase of WHMCSApps.com, WHMCS Services will continue to do customer sign-up, automatic billing, provisioning, termination and everything in between. Client support will continue to be integrated with support tickets and a comprehensive knowledge base. WHMCS Services will also continue to offer a dedicated Developer, and support for email, and much more.
 
About WHMCS Services
Based out of New York City, New York, WHMCS Services develops and deploys innovative software solutions for various web hosting providers throughout the industry. Our software programs are developed for both Internet users and Web hosting providers. Some of the most popular products in our menu are WHMCS Modules; we also offer SEO Service, WHMCS integration, SSL Certificates, SiteLock website security, custom works, Web design, affiliate marketing, and advertisement. We are a one-stop-shop for all your software needs. You can reach us at http://www.whmcsservices.com.
 
WHMCS Services was founded in 2004. You can find WS on the web at: http://www.whmcsservices.com and on Twitter at: https://twitter.com/WHMCSServices  and WS will be taking over the old WHMCS Apps Twitter account here: https://twitter.com/whmcsapps

###
Contacts:
WHMCS Services 
Email: pr (@) whmcsservices.com
Website: http://www.whmcsservices.com