How do I prevent changes to the things in "options"? Is there a master password?
My father-in-law has a habit of touching things he shouldn't. I want to lock down FF so he can't change any settings.
One thing you can do is to give him his own user account (non-administrator) on your computer. Then he will have his own Firefox user profile.
Firefox does have a Master Password feature, but it doesn't "lock preferences" in Options.
You can lock specific prefs with a mozilla.cfg file in the Firefox program folder. This effects all Firefox profile folders that use this Firefox program folder.