@simmerjennbob Start moving your files from the old Sims 4 folder to the new one. Where the game has created a new file or folder, it's best to use that rather than the old one, so for example don't bother moving over the many random files like config.log or notify.glob. For the folders like saves and Tray, move the files inside rather than the entire folders.
Start with anything in Mods you'd like to keep. Test the game again, and if you run into the same issue, you'll need to sort through your mods and custom content. The 50/50 method can make the process much more efficient.
https://modthesims.info/wiki.php?title=Game_Help:Finding_Problem_Custom_Content#The_50.25_Method
Once you've sorted through those files and your game is still working, you can move over the contents of saves and Tray, plus Screenshots and Recorded Videos if those matter to you. Then test one more time, and if everything still works, you can ditch the old Sims 4 folder and continue playing with the new one.