If I delete imovie, will all my files stored in "imovie library" also be deleted?

 just updated my MacBook pro (MacBook Pro (Retina, 15-inch, Mid 2015) to macOS Catalina. My iMovie stopped working and whenever I try to update it, it shows this message: "Movie cannot be updated because it was refunded or purchased with a different Apple ID". Please tell me what I should do as I don't know what Apple ID I used, as I downloaded the app 6 years ago. It has all my edited videos in the library and if I delete the app then I'm afraid all the videos will be gone. 

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