After selecting the songs for your iMovie Magic Movie, you can control the volume at which they'll play. Your options are: “Soft Music,” “Full Volume Music” or “Music Only.”
“Soft Music” will play subtly in the background of the video, making it easy to hear the audio from the original footage. “Full Volume Music” will play loudly and will compete with the original audio. The “Music Only” setting will only play your selected songs, and will not include any of the original audio from the tape in the final Magic iMovie.
All of the songs must use the same music setting. When you’re done, click OK.