Choose whether other users may add you to their friends list. If you are added to a friends list, the owner of that list is added to your list. When you remove someone from your friends list you are also removed from their list. Choose either:
Nobody may add me as a friend: no one may add you to their list.
New friends require my authorisation: your authorisation is needed for you to be added to a list. If you approve, they will be added to your list.
New friends are automatically authorised: anyone may add you to their list.