In IMovie Trailer, I have been trying to put a 6.7 second clip into a 2.2 second section of the trailer and it tells me my clip is not long enough. I don

It might be that the Trailer project is corrupted. Try creating a new trailer project and see if the problem persists.

If still problems, try deleting preferences. Open iMovie while holding down the Option and Command keys and select to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Now see if the durations are correct in your trailer project.

If still no luck, try redownloading iMovie. To update/redownload iMovie 10, drag your iMovie 10 app from the Applications folder into the trash, but do not empty the trash. Sign in to the app store and open your purchases folder by clicking on your name at the bottom of the app store side bar. You will see your purchases displayed, including iMovie 10. Redownload/update iMovie from there. If not successful, drag your present iMovie app out of the trash and return it to the Applications folder.

-- Rich