Can I turn off the video camera on Mac Pc and use another camera?

I need to record myself playing a ukulele using QuickTime Player but cannot use the Mac Pc built in camera. I need something that can get lower and closer which I have found and prefer to use. I can find no way when connecting my auxiliary camera to turn off the built in PC camera and use the preferred camera. Any recommendations or maybe different software?

Your expertise would be truly appreciated.