Imovie Audio Problem

[woodrz]

Hi I'm editing a school graudation video in imovie 5 hd and the sound from the video is playing through one channel only. Is there a way i can copy and paste that one channel inot the other so as to have both channels playing? The video will be played back at the school hall so i'm wanting to have both side of the hall able to hear the audio.

Thanks
Chris