Any way to control the volume on the PC App?

I have a $200 wireless headset and people complain all the time about not being able to hear me that well. It's so annoying. Thanks for nothing Logitech.

Anyways! What I usually do is turn the main volume down from the in game settings menu and I can hear everyone else just fine and then I can turn my headset volume up or down to make party chat louder so I can hear better and then turn in game volume down to compensate.

Well I found out that I can use party chat on my PC on the Xbox App. People say they can hear me perfect that way and it's really great and everything however there is one small problem.. Party chat comes through louder on my PC and you would think I could just right click on the sound bar in Windows 10 (bottom right corner) and go to volume mixer and just lower the volume of the app. WRONG. The app doesn't show up in the volume controls for some reason.

Is that a bug? Or is that just how it is? Is there a way to turn down the volume of the xbox PC app or just voice output from others/party chat?