Hi tone-dust,
Go to the Preferences, the Preferences Folder Button (left lower area), and the Library. Layout, you find the regular place where they should be stored.
If you go to your previous release and use the Main Menu> + >Save Layout as…, you will get to the folder that should contain it. If you stored them elsewhere, I can't tell.
Perhaps search for the suffix, but be aware that they might not work if they are for a much older version.
Search the ".l4d" and if you find it, copy the ".prf" into the current Layout folder.
I tested the R26 to 2023-1 transfer with a simple GUI change, and it worked.
https://help.maxon.net/c4d/2023/en-us/Default.htm#html/5220.html?TocPath=Configuration%257CGraphical%2520User%2520Interface%257C_____0
All the best