Multiple Users,changes not made to all

I am trying to add my brother as a user. I want him to have all access to
thing but I dont want his changes ( Moving files, changing icon on dest top)
to affect the computer and other users. I remember in the old widows when you
set up a account the first time you logged on it ask you to make it private
it pre vented changes you made affecting others accounts. I want the
computer to stay the same no matter what he does on his account. Please help