My administrator name didn't change like it was supposed to
My administrator name didn't change like it was supposed to
A few days ago, I tried to change my Macbook User name, from a nickname to my full name. Although I hit confirm, it didn't update. Now, neither name works and I'm completely locked out of changing anything within my System Preferences. There's no password reset nor help button. I'm reaching out in case anyone else has ever had this problem - I've tried restarting my computer, updating my Apple ID name and anything else I could think of. Whenever the prompt to enter an Administrator's name and password comes up, no matter what I enter, it won't let me back in.
I inserted below a picture of what I'm having trouble with, as I'm not sure I'm explaining this well enough. Whether I enter my nickname or full name, it locks me out. It also corrects me when I use my full name, and reverts it back to my nickname before I get in. I'm unsure if it's an issue with my iCloud or with my computer itself.
MacBook Pro 13″, macOS 10.13