Lock your Mac microphone with priority and fallback.

Choose the system input once

1. Open the Apple menu and choose System Settings.
2. Click Sound, then open the Input section.
3. Select the microphone you want as the current system input.
4. Speak normally and confirm that the input-level meter responds.

That is the right manual fix when the wrong device is selected now. Apple’s Sound Input guide documents the current macOS control.

Set microphone priority and fallback order

Mic Check lets you rank the system inputs you want it to protect. While protection is enabled, the highest-ranked connected microphone becomes the Mac’s system default. If another device or app changes that default, Mic Check verifies the change and restores your preferred connected input.

If the first choice disconnects, the next connected microphone in your ranking becomes the fallback. When a higher-ranked choice returns, Mic Check selects it again. An unranked device can remain connected without becoming a preferred input.

For example, put an office headset first and the MacBook microphone second. At the office, the headset wins. When it disconnects, the built-in microphone becomes the fallback. Leave AirPods unranked if you want to hear through them without preferring their microphone.

What “lock” means here

Mic Check does not prevent every attempted change. It restores the system default after a change occurs. It also leaves speaker and headphone output alone, so the listening device and the protected microphone can be different.

An app can still select a microphone by name inside its own settings. That app-specific choice does not follow the macOS default, so changing or protecting the system input cannot override it. See why an app can use the wrong microphone for the check.