control app volume with keyboard in win 10

[Windows Central Question]

I just got a keyboard with volume controls... is there a way to control the app's volume with it??? I can control the windows volume but that does not change the sound volume cause it does not change the app's volume. So windows volume can show mute but the sound meter is gray and still giving off sound... tried ear trumpet and that does nothing... taht does not cahnge the app's volume