Can't change my username

How can I change my username? I got sick and tired of my OLD username and I want to change it into “Teal-Brony” and it is suitable for me.

It says “You can’t access that page.” :(

You can only change your name once every 90 days, so I’m guessing you changed it recently? If so, report your own profile and request to have your name changed.

Thank you