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To set your profiles to public/private visit the profiles site. In the rightside user menu click on profile privacy link. Set the privacy level as you wish.
If you set your profiles to public it doesn't mean that all the profiles will be public.

Visit manage profiles and click the link manage profiles in the right side user menu.
The 'about me' profiles can be set to private or public by editing them. In the edit page for each profile, you can see the profile privacy checkbox at the bottom to choose.