Configuring audio settings to NOT switch to webcam microphone when it's plugged in?

[Adam Funk]

My laptop doesn't have a built-in webcam. Whenever I plug a USB one in
(I have one at home and a different model at work), the sound input
automatically switches to it, but I've been told that I sound better
if I use the built-in sound. So I have to remember when I start a call
to open the sound settings and change "Input" from "Webcam C270 Mono"
(or the other one) to "Built-in Audio Analogue Stereo".

Is there a way to configure the system so the sound input does not
automatically change when I plug the webcam in? (I'm using Ubuntu-MATE
22.04.4 LTS.)

Thanks.