Check the top part of the the post, it is for changing profile fields. The second part is for changing the sign up fields.

But watch out though, on my site I added extra fields to Create Account and Add Person, and one of my users cursed me out and demanded that the sign up process is too hard, so I removed all the extra fields from those two forms except for the recaptcha. I kept the other ones in the Edit Profile area. Then I went into my google repatcha account and changed the security preference to "Easiest for users".