I’m using macOS 10.14.6 and Audacity 2.4.2 It will not record from built-in microphone or Soundflower (2 ch) Quick Time Player records from built-in microphone. I wish to use Audacity to record an audio file playing with Quick Time Player. I have uninstalled and reinstalled Audacity two times with no improvement. I have used Audacity in the past with older versions with great success. 
Any help is appreciated.
Why not just Import the file into Audacity? (See: https://manual.audacityteam.org/man/importing_audio.html)
I have imported it into Autacity and it plays just fine in Audacity. Can I edit it? I ALSO NEED TO RECORD FROM MICROPHONE. It will not record from Microphone also.
What happens when you try to record from the built-in microphone?
Have you given Audacity permission to use the microphone? (in the Mac “Privacy” settings)
With your advice it now records from internal microphone. It still will not record using Soundflower (2ch). Other people have reported problems with Soundflower. Can you recommend an alternative to Soundflower for recording an audio file playing in the mac?
Fwiw, Soundflower works for me, but yes you are right, a lot of people have reported problems with Soundflower.
The original version of Soundflower is obsolete and no longer maintained, but there is a later version available from here: https://github.com/mattingalls/Soundflower (Read the "ReadMe.md " in the lower half of that page).
There’s an app called “Black Hole”, but I’ve never used that.
Thank you for your help. The later version of Soundflower corrected the record issue. All is well.