When you first sign onto FastCapture the settings page to change your Video and Audio Source will automatically pop up. If for some reason it does not, or if you accidentally click out of that window, simply click on the gear icon next to the video feedback on your screen.
Once you open your settings page, please locate the video source and audio source dropdown menus. Once there, all you need to do is select the desired source from the dropdown list.
Please Note: If you are using a capture card, your audio and video source will be the same, unless you have an external microphone.