I'm trying to make a short video using the built-in camera to record video and a USB microphone to record audio, but I cannot seem to make them work together. I changed the sound input to the USB microphone in system preferences, but it still records the audio with the built-in microphone. The only sound options I can find in iMovie are for voiceovers, and I don't want to do a voiceover, I want to record the audio and video at the same time. I really don't want to have terrible sound quality on this video, so I would really appreciate some help with this. Thanks.