CornerTable has three privacy settings so when posting, one of the following can be used:
Me=Obviously for self
Everyone=Public Post
and of course for friends only.
To keep postings to friends only, make sure the initial post is set to *Friends only* and the future posts will default to it.
Meantime , anything posted will by default public.
Eventually, people will come to this site who we don't like particularly much. We're all getting along now, but there is no reason to think it would stay that way, just as if you were on another social site you would not expect that. Please note, that we have some tools for blocking individuals as well. Rather than complain to site admins, use these tools.
Also, consider 'friending' only people you want to be actual friends, and limit the privacy of your profile posts to just those people, and keep your public facing content in a group, a page, or forum post.