If it doesn't helps, you could also choose the best iMovie for Mac alternatives instead. If your iMovie is now keeping crashing the latest macOS Big Sur, the following solutions may be helpful. If you were visiting Apple Community from time to time, you'll know there are people asking for solutions to fix iMovie crashing problem. iMovie could crash on startup, or while importing video from your Mac, or even when exporting your movie.
Problem Fixed: iMovie Keep Crashing Big Sur macOS
