With news that Facebook shows all your friends' data to companies when you interact with their Facebook apps, many people are interested in figuring out how to turn that setting off in their Facebook dashboards.
This is needlessly complex, because of course it is.
EFF's Gennie Gebhart has written up a howto explaining, step-by-step, how to undo this setting that a) shouldn't exist and b) shouldn't be on by default and c) should be one click to turn off.
Log into Facebook and visit the App Settings page (or go there manually via the Settings Menu > Apps ).
From there, click the "Edit" button under "Apps, Websites and Plugins." Click "Disable Platform."
If disabling platform entirely is too much, there is another setting that can help: limiting the personal information accessible by apps that others use. By default, other people who can see your info can bring it with them when they use apps, and your info becomes available to those apps. You can limit this as follows.
From the same page, click "Edit" under "Apps Others Use." Then uncheck the types of information that you don't want others' apps to be able to access. For most people reading this post, that will mean unchecking every category.
How To Change Your Facebook Settings To Opt Out of Platform API Sharing