I took a video on my iPhone 4, uploaded it to my computer, and imported it into iMovie so I can edit the sound. At a few points throughout the one minute clip, my voice is overbearingly loud since I'm holding the phone nearest to me... and I'd like to adjust the sound (I guess simply decrease the volume?) at these few points where my voice overpowers the rest of the video... so as to make it less awkward for myself, really... before I share the video with any of my friends and family. How would I go about this to just edit the volumes of a few short segments?