Facebook recently announced that it's going to use your browsing history so they can give you a better advertising experience, because that's always at the top of your wish list. That goes for your mobile and desktop/laptop browsing history. Luckily, there's a way to stop it.
Once there, select the Companies Customizing Ads for Your Browser button.
Click "Facebook" and any other sites you want to opt-out of, and then scroll down and hit 'submit'.
Next, it's the mobile department.
If you have an iPhone, go to settings and go to Settings, General, Restrictions, and then Advertising, then click "Limit Ad Tracking."
If you have Android, go to Google Settings, Ads, Opt Out of Interest-Based Ads, and boom, you're done.