i'm changing usernames on 470 with the following commands:
username "operator" "userp@ss" ro
username "admin" "adminp@ss" rw
Quotes are not important. It changes username on switch or stack depending what it is at the moment.
What is your software version? Older software, (i've met 2.2, 3.1 and 3.6) doesn't have "username" command at all, but i've never seen syntax as you have. I think upgrading software will help, 3.7.2 at least - no problems there.
John T
yes, 4500 and 5500 can't change username. Really there is no username at all.
But 470 can do that.