You can record system audio with Background Music. With Background Music running, launch QuickTime Player and select File > New Audio Recording (or New Screen ... Issues 508 · Pull requests 0 · Discussions · Security
On your Mac, choose Apple menu > System Settings, click Accessibility in the sidebar, then click Audio on the right. (You may need to scroll down.).
I'm trying to run Zoom and Youtube videos (on Safari) at the same time. I want to be able to lower volume on one to listen to the other -- and switch back and ...