How do I change the device audio volume?

Hello!

I'm trying to access the main audio volume of the device on which I'm testing my app (Android or PC). But for now, I just managed to change the actual volume level to itself, or 0.

I have this:

And the code looks like this:

-2 is actually -20, to follow the popup tip. And 45 is 450, the width of my black line, the volumeBG.

For example on Windows 10, the sound volume still stays at 6, not matter what I specify in Construct.

Is there something I didn't find?