When you first join Highrise, your profile is set to "Public". That means anyone and everyone can see your profile and posts. Don't fancy sharing your profile with everyone? Not to worry!
Navigate to your profile page, give the 'Edit Profile' button a click,
On this page you'll see all your privacy settings, simply set them to the privacy levels you wish, and you're done!
Oh, and remember, your followers? They're your biggest fans! They'll always see your latest posts popping up in their Newsfeed (and you'll see theirs). After all, it's only fair, right?