Microphone!

Newbie here. I wonder if anyone can help. I’ve an Acer aspire laptop. I downloaded a couple of different programs that I was hoping to use for a jamming session with my guitar.

Jammr and Sofasession are the two but unfortunately they don’t work. I’ve uninstalled them both but I’ve been left with a real annoying problem.

when I watch, for eg YouTube the in built mic is on and if you touch anywhere on the laptop you can hear crackling and noise. It only goes off if I turn speakers off. I’ve tried everything I know about disabling the mic but nothing work.

Can anyone please help. This is driving me crazy.

Thank, kind regards

David