FCP and MOTION Crash at Start-up. Where's the corrupt shared file

I need serious help... please.
I upgraded to Catalina and I'm running FCPx 10.4.8

FCPx and Motion were both running great for days. Then one day FCP would not open at startup. I have tried every trick on the internet, and nothing. The one thing that worked was starting a new login account and BOTH PROGRAMS RUN in the new Login.

So it is not a hardware or compatibility issue. It has to be a corrupt startup file that both programs share.

Can anyone tell me how to delete every start-up file so that i can start fresh. I tried re-installing FCPx, but it crashed. So it is corrupt file somewhere in the library.

It can also be a plugin. Where are these plugins and their preferences.

In the end, I would like to wipe FCPx and Motion clean and start adding my plugins one at a time.

I have the error file if anyone wants to see it.

Thanks

You need to delete a file or two for the user account to fix that issue.
appletoolbox.com/fix-corrupt-user-accounts-macos/