I'm having trouble figuring out how to rename a user name on my mac. I inherited it when I transferred data from an older mac. I no longer have that job title and I just want to change it to my name. The name & extension text box is greyed out and i am unable to change it. But the "user" doesn't show up in the users and groups tab of system preferences. I'm hoping this is a basic problem that someone has an easy solution for!