Something interesting happened. I used my manually backed up settings
copying the entire folder
AppData\Roaming\GPSoftware\Directory Opus
to a new installation. Seems everything transported, except one personal toolbar that was hidden. I had to recheck it to view it. Where is that setting stored that it was not transported?
It's stored in the same folder. I suspect something more complicated is going on, like you have layouts (or a default lister) with custom toolbars and opened a different layout or similar.
I also noticed it didn't remember if a folder was in thumbnail or details view.
Because I automatically backup every 10 days in a new file and keep the last 50 backups and it deletes the old ones. Can the built in backup do that? Didn't try it.