First make sure you are running the game with admin rights, most home users user admin logins for their main login but you never know. Second search for a file called "ffxiv.cfg" in your documents section. This has all the game operation settings in it. I suggest you rename it to "ffxiv.old" so it will rebuild itself when you open the launcher next, if you still have an issue this file was not the issue and you may need to try a few other things.

(You rename that file instead of deleting it so you can change the name back if it was not the issue).