Go into System Preferences – Sound – Output - choose Multi-Output Device.

Place a checkmark next to SoundFlower 2ch and Built-in Output.

Place a checkmark next to Soundflower 2ch and Built-in Microphone.

Click the (+) Plus sign in bottom left corner.

Go to Applications – Utilities - Open Audio Midi Setup.

NOTE: If you do not want to include your microphone audio and only include the audio from your computer in your screen recording, just take out the steps related to the “Aggregate Device” and choose SoundFlower 2ch in QuickTime for your screen recording. This was the exact thing I needed to do when I figured this out, thought I would write it up to remember in the future. This is great for a screen-sharing session where you are talking to someone and walking through an application over the computer. The Holy Grail (Adding Audio from your Microphone and your Computer while being able to hear the audio as it records)

Start New Screen Recording – Click drop down arrow on right side of dialog box – choose Soundflower 2ch.

Go into System Preferences – Sound – Output - choose Soundflower 2ch.

This option routes ALL audio through Soundflower and therefore you CANNOT HEAR IT to monitor it as it is being recorded. Google “Screen recording with audio on Mac” and you will see.

This is what I kept finding when trying to search for a solution. This allows you to capture the audio from your computer in your QuickTime screen recording. You can install Soundflower to route your computer’s audio back into QuickTime to record it. However, when doing so, you only get the screen – no audio. QuickTime allows you to easily do a screen recording. The Holy Grail of screen recording on Mac

How to record a video on mac screen