27 XPS HDMI PORT Audio issues

I received an Nintendo Classic NES System and I've connected it via HDMI to my XPS. The volume is at 100 and won't allow me to lower it. It's super loud & annoying as you can imagine old 8bit games with their low budget sound effects...

Anyway, I have a Bose system connected to this computer as well -but the volume used when I play the NES switches to the computers speakers-not through the Bose. I'd like it to be connected to the Bose and control the volume that way but, I'll settle for either-for as long as I can turn down the volume...

Thanks in advance..!