I am very grateful for the free use of this great add-on. I have some revisions that you may like.
1) ACTIVATION of ADD-ON, CTRL+3, should ALSO work in FULLSCREEN.
2) When opening new TABS, option = A) open TAB with AUDIO reset to normal. B) open TAB with the "600% Sound Volume" add-on setting, that was previously used.
---> Presently, option "A" is default and is not optional. (Having an Option "B" would be my choice since I run the "600% Sound Volume" add-on, at 300% for every TAB, to match the output levels of my computer, with the input levels required by my external sound system)
---> EDIT: It's 8 months since I made these suggestions, to my knowledge, there is no evidence that they even read my suggestions, let alone implement them. Those changes are simple, I think I'll see if someone else has that feature.