Once you are logged into LinkedIn, you can change your setting by going up to the ‘Me’ menu at the top, and selecting ‘Settings and Privacy’:

This will open up another tab.  Go to the ‘Privacy’ tab:

A couple of items to pay close attention to in here: 1) If you are not interested in the public seeing your profile, you can limit this through the ‘Edit your public profile’ page.  There are many items that you can tweak here as well as limit your full profile to only your connections.

2)  You can also limit what others see when you look at their profile through the ‘Profile viewing options’.  This allows you to look at other’s profiles anonymously if you wish.  The last item of note is this page is also where you can set Two-step verification to better protect your account.