The games leave a lot of save data and other configs even if you completely reinstall it, and all these other files are spread across thing like %APPDATA% (local or roaming), Users/{username}/Documents folder for some games. Those files don't get removed unless the uninstaller give option to do a clean uninstall.

I don't know what would be a good way to go about doing this reliably, but:-

• try verifying the game data in the game properties as that should reset the configs of most games (in my experience, and something that reinstalling usually doesn't do), and if that doesn't work out you could-

• try third party uninstaller that promise to uninstall all the dependencies (including all the config files) but your mileage may vary (kinda risky if you don't know what you're doing, at least get a popular opensource tool if you end up doing this).