Mainly the users folder(s) e.g. c:\users\YOURUSERNAME , the hidden appdata\local and appdata\roaming folders in there probably contain way more than you actually need to back up but you could back up the whole thing to be on the safe side. Most of your user’s program configuration data is in those folders.

Sometimes systemwide program config data is in the hidden c:\programdata folder but I wouldn’t back that up aside from specific programs you really want to save config info for.

Aside from that any other folders you created containing data you care about.

And like the other comment mentioned, the Windows registry also has lots of program config data but I usually skip that, the majority of it is useless… but if there’s a great need for you to export a specific registry tree you could do that via the command prompt to export to a backup text file. I think reg export would do it https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/reg-export