Problem:

When I open ZenTuner it automatically selects the default input microphone which is usually the Macbook microphone. When I change the default macbook microphone, the app doesn't update the input device either.

To resolve the issue, I need first to set the audio interface (where my guitar is plugged in) as the default macOS mic. Then open/reopen ZenTuner.

Possible improvements

It would be nice to have a way to select which input device I want to use or even make the app automatically update the microphone when I update the default input device.