I've tried everything that the mighty google will give me as possible solutions, but nothing helped. I have been running into a strange problem for quite some time now and would like the help of this fine subreddit: When I change anything in the ingame options menu in Sim City 4, those changes won't get saved when I restart the game.
After entering the UserDir parameter again, those changes in the options menu were still active, so this is a workaround. But when I deleted that parameter, I could change and save the settings. I tried it even with a very simple UserDir path (no special characters etc.) and it didn't work. I tried around a little bit and all other parameters I used didn't have an effect. NimX3 gave the decisive hint: It seems like Sim City 4 doesn't save changes in the options menu when it runs via a shortcut that uses the -Userdir:"C:\XYZ" parameter.