When we first set up our Macs we tweak and adjust settings to suit our own personal preferences. The worst thing in the world is when someone comes along and doesn't respect our Mac. We've all experienced it from time to time. They pop into System Preferences like they own the place and start changing things like trackpad speed, display resolution, and who knows what else. We are left appalled when they're done. Luckily, OS X has a neat little trick to keep people from doing all these terrible things. Here's how:
That's all there is to it. While there isn't any password protection for System Preferences in OS X (even though there should be), this is a neat trick that should keep anyone out that is on your computer for only a limited amount of time, unless they also know about this trick. In that case, you're out of luck and would be better off just creating a Guest account.
And remember, for some of us changing our System Preferences is just as bad as rearranging our living room furniture. Don't do it!