Ps4 save file problem

OK, finally got a new console about a month ago. A younger "relative" (we'll call him Fat frick, FF for short) came over, and asked if he could play the PS4. No problem. After he leaves, I turn it on and see he made his own user profile. Still fine. What wasn't fine was when I realized FF's profile now has all my saved data on it. I don't know what the little bastard did, but I'd kind of like to have my shite on my profile. Any suggestions?