QuickTime - Record internal audio and not external audio

My goal is to record my screen with internal audio, but leaving out external audio. I tried solutions with Soundflower software, and it works for the first part.

I cannot mute my external audio. Do you have any suggestions?


There is a shareware/free software designed specifically for this task called BlackHole which I use on a weekly basis. Here is the developer's website and here is his project on GitHub.