cannot adjust volume in imovie '08

[Nadasive]

i used to be able to put in my mp3 over a video and i would put the music to about 10% volume and it would play nicely in the background. half my video is done like that and i am trying to add more mp3's to the rest but when i add em and try to edit the mp3's volume it gives me a little red line over the clip with a dot in the middle? what do i do?
i tried deleting com.apple.iMovie8.plist but i cant find it anywhere.

 

[Nadasive]

I need a fix to this asapp pleasee someone help me !

 

[Nadasive]

i go to edit > page adjustments and everything there is unclickable. Video Audio and Crop.

 

[Dave Braine]

tried deleting com.apple.iMovie8.plist but i cant find it anywhere.

It should be in Home Folder>Library>Preferences.