Changed OSX 10.13.6 username. Can no longer sudo

User accounts -> change username. I didn’t change the home folder, Just display name + user name.
But, that didn’t work? I see my old name “quantum” in the login
I don’t see my new username

I’m unable to sudo. “quantum is not part of the sudoers, this incident will be reported”

I’m pissed at the UX here. A few clicks and I no longer have sudo access.

I can’t use the new username when logging in. Is my installation completely broken?

dscl . list /Users