Administrator now cannot chagen data in personal page (admin/users/viewuser.action). Why?

My problem no. 1: I must change internal phone number.
My problem no. 2: I must change welcom page for new users (with describe Confluence).
Virtual problem: User have vulgar words or picture in profile page.

Action now: I must change password, login as one user, change data and logout. User must activate Forgot password, view mail, login and change password.
It's not easy for global change.