Stereo Mix

Forgive me if this in wrong section.

I have a problem.
Before I has been able to use stereo mix on PR-mumble, and through there play music that i self listen to and so on.

But now latley the “Input” tab and the stero mix, right to it there is like a bar that shows how much sounds that goes through it.
No matter how high i play or try any settings it wont budge, and i have asked mates if they can hear what i play, and it still does not work…

How can i fix this?

This isn’t a Forum about gaming or smartphones.

Unless you are asking about Audacity or something to do with audio on Windows, Mac or Linux, please ask elsewhere.