KbCheck in while loop - recording button presses several times

Diedericks advice is th correct one.

Btw. your priority support is used up, as the question you asked a while ago already exceeded the 60 minutes of total time contingent, clocking in at 73 minutes. You’d have to buy a new license for further support by myself.

Also, relating to your old audio question: You could UpdatePsychtoolbox to PTB 3.0.18. It had some improvements to the PsychPortAudio sound driver, which may be able to work around macOS audio volume deficiencies. Seemed to work on my Catalina MBP 2017, maybe it also helps on yours.

For reference, this was the verdict under PTB 3.0.17 + macOS:

-mario