How to Configure Your Mac OS X Snow Leopard Login Screen for Multiple Users
If you plan for more than one person to use your Mac, you'll want to set up your login screen to accommodate multiple users. Mac OS X Snow Leopard allows you to display a list login screen, a login screen with a username and password, or one automatic login method that doesn’t display the login screen at all.
To specify which type of login screen you see — if you see one at all — head to System Preferences, click Accounts, and then click the Login Options button.
With Automatic Login set, Mac OS X Snow Leopard automatically logs in the specified account when you reboot. In effect, you never see the login screen unless you click Log Out from the Apple menu. This is an attractive option if your computer is in a secure location, such as your office, and you’ll be the only one using your Mac.
To set Automatic Login, display the Login Options settings and click the Automatic Login pop-up menu. Choose the account that automatically logs in from the list. When Mac OS X displays the user Name and Password sheet, type the corresponding password and then click OK.
Never set the Automatic Login feature to an admin-level account unless you’re sure to be the only one using your Mac. If the computer is rebooted, you’re opening the door for anyone to wreak havoc!
Logging in with usernames
You could choose to require Mac users to select or enter a username and a password. You must again visit the Login Options settings pane. Select the List of Users radio button for a list login screen or select the Name and Password radio button for a simple login screen where you must type your username and password.
Logging in with a list: To log in, click your account username in the list, and the login screen displays the password prompt. Type your password. Mac OS X displays bullet characters to ensure security. Press Return (or click the Log In button).
Logging in with username and password: Type your account username in the Name field and press Tab. Then type your password and press Return (or click the Log In button).
Logging out and switching users
To log out of Mac OS X without restarting or shutting down the computer, choose the Apple menu and then choose Log Out or just press Command+Shift+Q. You see the confirmation dialog. Although Mac OS X displays the login screen after two minutes, someone can still saunter up and click the Cancel button, thereby gaining access to your stuff. Therefore, always click the Log Out button on this screen before your hand leaves the mouse, or bypass the confirmation dialog altogether by holding down the Option key as you click Log Out from the menu!
You can also enable Fast User Switching from the Login Options panel. This feature allows another user to sit down and log in while the previous user’s applications are still running in the background. When you enable switching, Snow Leopard displays the currently active user’s name or account icon at the right side of the Finder menu bar. Click the name, and a menu appears; click Login Window, and another user can then log in as usual. (From the Login Options pane, you can also choose to display the current user by the account’s short name or the account icon.)
Even though you’re playing musical chairs, the Big X remembers what’s running and the state of your Desktop when you last left it. (When you decide to switch back, Snow Leopard prompts you for that account’s login password for security . . . just in case, you understand.)