OS X Mavericks: If you don’t see a login window when you start your Mac
If your Mac starts up without displaying the login window, it’s set up to bypass the login window and automatically log in a particular user.
If several people use a Mac, it’s best to add a user for each person and turn off automatic login. Having separate users protects the information and settings of each user.
- Choose Apple menu > System Preferences, click Users & Groups, then click Login Options.
- If the options are dimmed, click the lock icon to unlock it, then type an administrator name and password.
- Choose Off from the “Automatic login” pop-up menu.
The next time you start up your Mac, the login window appears, and a user name and password are required to log in.