Having same problem as unresolved thread started in Oct. 2021 titled "Microphone Constantly Switching". The original poster says they accidentally marked as resolved but it isn't. The solutions suggested by Zoom Moderator CarlaA in that thread don't help. I too think this started as of the last update. Zoom constantly switches between the microphone on my closed laptop and my high-quality external microphone, popping up windows as it does. The microphone I've manually chosen in the "Audio Preferences" is the external but Zoom takes control and rapidly switches back and forth so that I come through so broken up that no one can understand me. I bought the external mic because even having my computer open and off to the side the built-in mic on the laptop doesn't pick up. The only way I'm able to use zoom at the moment is to run one session on my computer for video+speaker and a second as a call-in on my phone to be my "microphone." It would be nice for Zoom to trace this down and fix it. One solution is that Zoom could disable the auto-switching on the mic audio so that users actually do have control over their input source.