I've been spoiled by my ability to control the volume (or mute) any individual program running on my computer. I just tried a Modern-UI
game from the store and it was shockingly loud, so I did what I normally do – go to the audio mixer to mute it.
It didn't show up in the system volume control! Is there something I'm missing? Is it truly up to every individual application? Can I mute all Modern-UI apps without muting all audio?
Best Answer
There seems to be no way to control the volume of individual Metro apps from a single interface, which certainly seems like a step back to me.
All you can do (in most cases) is select Settings from the Charms bar (Win+I) and click the speaker icon, or use the desktop volume control from the tray/notification area.
However, if an app does provide its own volume control you should be able to locate it by looking under its own Settings in the Charms bar.
Edit: Apparently, not only is the lack of a Metro audio mixer by design, Microsoft is also discouraging devs from including per-app volume controls as per this MSDN blog post:
(Note: Substitute "simplify" with "dumb down").
Edit 2: While a third-party volume mixer called EarTrumpet has enabled this functionality on Windows 10 since July 2015, it has shamefully taken Microsoft nearly 5 years to finally add Metro/Modern/UWP app support to Windows' own volume mixer in the Windows 10 Insider Preview Build 16193: