In Presenter view you can adjust your camera and microphone settings at any time using the "Settings" button near the middle of the presenter controls.
The Settings button will open the presenter settings modal which allows you to choose which camera, microphone and speakers are used.
Presenter settings modal
Click "Save settings" at the bottom of the modal to apply the new settings. Once the new settings are saved, they will immediately be applied, even if your camera is currently live.