iMovie Constantly Crashes

I have had my Mac Book Pro in and out of the apple store about 5 times now. iMovie will crash CONSTANTLY!!! They replaced the RAM and Logicboard which fixed the problem for about a week. I cannot seem to figure out how to delete the iMovie preferences. Cant fint the com.apple.iMovieApp.plist file anywhere trust me, its not on my computer. I have also uninstalled and reinstalled iMovie. The scrubbing in the editing will stop working and the video will freeze and it crashes 100% of the time when previewing the project in fullscreen. I have sent literally 1000 crash reports to apple which I find useless because nobody has any record of them, not the Apple store, not Apple support, not Steve Jobs..... Anyone have this problem? Please Please help me before I lose my mind. Thanks in advance...😠