As stated in the description, it only works on HTML5 video, which site did you try to change the volume on? It works but some sites have CSP rules that block it from initializing/breaks audio. Add those sites to the blocklist in the settings. More and more sites have been adding CSP rules to block extension manipulation to fight off exploits and bots...

Hello, I made the icon more of a silver color now, with some black outline. Hope you like it. Can you please revise to a higher rating? :D