Hello, I am using version 32.0.3. Sometimes Firefox will need a restart also when using my fix.
Please note, though, that this fixes issues with YouTube and other sides like VideoWeed, and similar, but not what has been mentioned here. However I assume that the fix should work here too.
Hello. I apologise for reviving an 8 month old post, but I’d like to share what I treat as *always* the solution when this happens to me.
Whenever Firefox either stays mute or plays through the wrong device, the main device reads as being used by another program if you try to test it in the sound control panel. To fix this, restart the Windows Audio Service. (In Windows 8, open task manager, go to the services tab, and search for Audiosrv. Right click, and restart it).
Hope this helps.