The Notifications are in the Browser itself and not as Windows Notification! What was the whole reason to start that project.

but no worries if you really want windows notification there is a setting
select which channel sends a notification and quick check all/uncheck all and a lock option to prevent accidentals (list only)
Oauth Login on Twitch to import/update every 30s your follow list + manual import if needed
manual add Channels to get Notifications without the need of following (highlighted yellow)
can choose 4 locations/positions of the Notification
choose in which browser Window you want the Notification (All, specific Window or active Window)
custom Notification lifespan slider (1s-60s) + a never disappear option
in-page notification sounds + volume slider(none and 5 options to choose from) (system notifications use windows sounds that are controlled by windows)

Planned features:

UI/design overhaul to make it look pretty(partially already started WIP) :)
remove the remove button on automatic added channels
change the remove button to a purple X on manual added channels
game name smaller under channel name

Maybe planned features

favorite streamers so they stay on top of the list
Different Themes/Custom Design/Colors

Limitations: In-Page Notifications does not work on Mozilla related pages like addons.mozilla.org, internal pages like about:addons or other add-on option pages (e.g. moz-extension://*). This is because Firefox restricts add-ons from accessing these pages for security reasons. In-Page Audio for notifications also only plays if the audio auto play settings is enabled on the current tab/website (if you are on sites that block it as default you will not hear it - you can have both In-Page and system up but be aware that you get 2 sounds every time ;)) Permissions explained:

Display notifications to you: This is used to show a notification in-page and/or on system messages
Access your data for all websites and Access browser tabs: This is a key permission, because the notification is shown on every webpage you visit (which means a part of the code is running in each tab).
To my knowledge this is how it works. If there are some errors or missing or not required permissions let me know

Medivha

Published Firefox add-on:

Twitch Browser Notification