If you have multiple camera or microphone sources connected to the device you are using to go live, you can switch between these different cams and mics at will so you can offer the highest quality show possible!
To change which camera and microphone are being used during your live session, click <Settings> at the bottom of your live room.
This will bring up a menu which will show the current devices in use. If you click these, a drop-down will show you a list of all your available devices. If you don't see the device you wish to use, make sure to disconnect and reconnect it as you should see it become an option.
Click the new device to switch over and you should see this take effect immediately!