Or Alternatively you can use the marque tool to select all the audio clips you want to adjust the gain on.
then right click on one of them and select Audio Gain
set the level, hit ok and all your clips will have the same gain settings applied to them.
this is a blanket operation though, if one clip out of 10 already has 4db on it and you set the new level of the 10 clips to 8db, your 4db clip will also go to 8db
kinda annoying, but thats the way it works
~Peter Berthet
Sydney, Australia