First thing regarding trimming, I don't use it, it is too complicated......If you want it simple just use the split function and delete the parts you don't want.
1. Find the start of the section you don't want on the timeline.
2. Right click and select split.
3. Move to the end of the section you don't want.
4. Right click and select split.
5. Click on the selection you don't want and hit delete.....all done.
If you have multiple tracks underneath each other you want to split.
1. Use the same procedure as above but use the control key to select multiple tracks which will activate the multi-split icon above the timeline.
Now that took longer to type this out than actually doing the splitting process.
I hope that helps.
Cheers
Robert2 S
My youtube channel====> http://www.youtube.com/user/relate2?feature=mhsn