How do I pick which mic to use for RINGR Desktop?

When you first connect to a call in RINGR desktop it will prompt you to allow it microphone permissions:

Click allow so that the app can read and manage the microphone settings. 

Afterwards, the audio input selector will be displayed (on subsequent calls you may not be asked for permissions again, but you will be asked to select audio input and output settings for every call):

If you need to change your audio input/output settings, please close the call window and re-join the conversation.