How to set a default audio output device on macOS

Changing it in System Settings

Open System Settings ▸ Sound, select the Output tab, and click the device you want. The change takes effect immediately, and applies to everything — macOS does not have per-app output routing built in.

The Input tab works the same way, and is worth checking separately. Meeting apps often pick up the wrong microphone, and input and output are chosen independently.

The faster way most people miss

You rarely need System Settings. Option-click the Sound icon in the menu bar and you get the full output list, with the current device ticked. Click to switch. Holding Option is the part people do not know: a normal click only shows the volume slider.

No Sound icon? Turn it on under System Settings ▸ Control Centre ▸ Sound and choose Always Show in Menu Bar.

Why your choice does not stick

macOS has one rule for choosing your audio device: whatever connected most recently wins. There is no notion of preference, and no way to tell it that one device matters more than another.

So your selection holds right up until the next thing connects. Plug in a monitor, open an AirPods case, dock your laptop, and macOS hands the audio to whatever just arrived. You did not lose the setting — macOS simply never treated it as a setting.

This is also why the problem gets worse the better your setup is. The more audio devices you own, the more often something becomes "most recent".

What about per-app output?

macOS has no built-in way to send one app to one device and another app somewhere else. Third-party tools can do it, but it requires intercepting audio, which needs a system permission and is considerably more invasive than simply choosing a default device.

For most people the real want is not per-app routing. It is for the Mac to stop changing its mind.

Making it permanent

If you want a default that actually behaves like a default, you need something that re-applies your preference whenever devices change. Tunestack lets you rank your outputs once and then keeps audio on the highest-ranked device that is genuinely connected, instead of the one that happened to connect last.