Facebook - Profile changes & recovery after scam or malicious attacks
When Facebook users click on a malicious link, it may alter Profile settings that need to be repaired and better secured as noted in link below:
How to Clean Up Your Facebook Account After Getting Scammed
QUOTE: Have you clicked the link to a Facebook message like that? Typically it brings you to a survey at which you're asked to install an application. If you follow all the instructions you'll end up spreading the same things to your friends. This sort of thing is really common on Facebook. Thanks to Graham Clueley for writing a blog and video on how to clean your profile up after making such a mistake. Here's the video.