I can’t change my profile photo to one of my older ones!

Try holding and dragging the photo you want to last place in the My profile photos album.

Alternatively, you can open the photo and press MorePhoto editor. After this, make some changes to the photo (move the blur slider a little bit or add a gap in the text), save it and try to set it as your profile picture again.
Your search for returned no results.
Try using other keywords, e.g.: "delete profile", "create chat".
Check your request for misprints.