MacOS Catalina 10.15.4
1. Close Lightroom.
2. Hold down [Alt/Opt]+[Shift] while restarting Lightroom.
3. Overwrite the Preferences when prompted by the dialog.
4. Close Lightroom.
5. Restart Lightroom.
It's pretty painless, just go over your preferences to reset anything that changed (not a lot changes), takes 5-10 minutes.