The System Preferences window is another area of your computer that you can password protect, and it's an important one. It provides access to settings that determine how your Macintosh behaves. You don't want just any user (such as your 10-year-old son) to change the way your mouse or keyboard works or make your Macintosh start up using a different hard disk, for example. If someone accesses the System Preferences window without your knowledge, he or she can literally change your Macintosh. Think of the System Preferences window as the keys to your computer's "house"; you wouldn't give these keys to just anyone, nor would you give them tools for ripping out the carpet and knocking down the walls.
To control access to System Preferences, password protect it like so:
Click the Apple menu and choose System Preferences. The System Preferences window appears.
Click the Security icon under the Personal category. The Security window appears.
Click the General tab. The Security window appears (see Figure 52-1).
Click the lock icon in the bottom-left corner of the Security window. (Skip this step if the lock icon already appears opened.) When a dialog appears, type your password and click OK.
Select the Require password to unlock each System Preferences pane checkbox.
Click the close button of the Security window.