I am starting to dislike current situation of handling sound under Linux.
On my desktop I am using Fedora which is using PulseAudio to handle sound. And recently something changed cause I have to reach mute button too often.
Normally I have Deezer in Chrome playing some background music with volume in web app set to the highest value. I can use KDE mixer to control how loud it is and it works fine. When I run YouTube, Vimeo it is fine. Adobe Flash videos? Fine as well. And according to PulseAudio mixers it keeps stream value at same level every time.
But I do not like that browser. I use Firefox for most of my web stuff. But every time I play YouTube video it jumps with PA stream volume to the highest possible setting so even my next street neighbors are probably able to hear it. Sure, I can change YT volume to nearly zero but when will have to do it with all other web applications as well (and many of them do not have loudness control).
MPlayer (which I use for movies) plays nicely with volume - alters only own PA stream volume.
I think that it is a time for me to report bug against Firefox.