I've been trying to edit my profile (name, username, bio, profile photo). It says changes saved. Yes, it changes. Just for seconds. When I reload it, it appearing the same information (my name, username, bio, and profile photo). When I comment on a post, it's written my old username. But I can't log in with my old username. (So, i log in with my new username). I look my account from my friend's account, it keeps appearing the same information. I search my account by wrote my new username) and it says "user not found" .
How can I do to change it successfully?