No matter how securely you've locked down your Facebook account, you can't make your profile pic and cover photo private.
Whatever Facebook's reasons for the policy -- maybe it's just so you could verify an acquaintance's identity before adding them as a friend -- it's long been a part of the social network. But as a privacy consolation, you used to be able to make your profile pic "unclickable," so that nobody, not even your friends, could click on the picture and see the full-size version.
Well, I have bad news. Facebook recently changed this privacy setting (without telling anyone, of course), and now your main profile picture is always clickable by anyone, even if they're not a friend. While strangers previously saw only a 160-by-160-pixel version of your profile pic -- large enough for them to determine if they knew you, but small enough to keep them from doing anything sketchy with it -- now they can see the whole thing.
I don't like this change, even though Facebook has added some privacy precautions (for example, if you set your picture to "Only Me," strangers won't be able to see likes, comments or photo data associated with the photo -- just the photo itself). So, if you want to keep your profile pics as private as they can be, here's what you need to do.
Step 1: Change your profile picture
One privacy precaution Facebook added is an updated cropping tool. Up until recently, the site's cropping tool didn't actually crop your profile picture, it just cropped your picture for the small version and displayed the full photo when you clicked on the thumbnail. Now, the cropping tool crops both your small photo and your full-size photo into a square (of two different sizes, of course).
Just be aware that if you're using a profile photo cropped with Facebook's old tool, people will still be able to see the full, uncropped image when they click on it. That could be a problem if you were strategically cropping something out. If that's the case for you, consider deleting the photo and uploading it again.
Step 2: Use a small photo
If you don't want your high-res photo splashed all over the Internet, crop and resize it prior to uploading it. Using an imaging tool such as Adobe Photoshop or Microsoft Paint, crop your photo into a square and then resize it to 180 by 180 pixels.
When you upload it to Facebook, it will be just a hair larger than the small version of your profile picture, and when people click on it, they won't get a blown-up version.
Step 3: Change the individual privacy settings of your current and past profile pics
By default, all of your profile pictures are public. In other words, not only can strangers view the full-size version of your current picture, they also can flip and previous profile photos that you haven't deleted in their full-size glory.
To change this, open each profile picture and go to Edit, click the privacy button, and under Who should see this?, choose More Options and then click Only Me. You must do this separately for each photo in the album, including your current profile picture.
If you leave your current profile picture set to Public, then strangers will be able to see likes, comments, captions, and other photo data, such as location and tags.
If you change it to Only Me, they will see just the photo and nothing else.