how to make user can't change their username

i've been search all your database but can't find correct answer for my problem

in my forum, all user can change their username. how can i disallowed them to do that.

thanks for the advance

Administration Panel -> Users & Groups -> Users -> User Settings -> Scroll Down -> Allow users to change their username

~Uber Lord

to be precise ,

go to Administration Panel -> Users & Groups -> Users -> User Settings -> Scroll Down -> Allow users to change their username > NO > save

ty

sorry for late reply, i solve my problem already. thanks to both of you