su not possible

I installed with live cd. I created my user with password. In terminal I can’t use su the password is not the same as root.

How can I change the su password.

Usually this is because your normal user is not in the wheel group.

@ # gpasswd -a user-name wheel @

You’ll, of course, have to login as root temporarily to make that change. Let me know if that works for you.

OK, thank you. It works.