How can I prevent comments I make on pages viewed in Firefox from posting to Facebook?
Some websites use Facebook as their commenting system. So when you comment it can post to Facebook as well. There is usually an option of posting to Facebook or not posting to Facebook, so look for that and uncheck the box before you post your comments on whichever sites you are referring to.
you login to that sites with your facebook profile, al you need to do is go to facebook, go to settings, apps, and on your right you got a list with all the apps that got access to your facebook profile and who can post messages on your name . you can remove that apps by clicking on the "X" in the right