Macbook Pro 2017 running on macOS High Sierra. Okay, so I can log into my computer fine (so far) but if I were to try to make changes, like in System Preferences and it asked for my Admin Username and Password, both slots show up empty and if I put in my username and password as they are, it won't accept it. I am still on my admin account by the way. Yes, I was one of those idiots that ignored the warning when I went to Advanced Options that I might not be able to log in if I changed that info. I had just really wanted a new username in the corner of my Macbook *sigh* How can I fix my mistake?