OS X Mountain Lion: Quickly switch between accounts
If your computer has multiple users, switching between users can be inconvenient. Normally, you have to log out before another user can log in. You can turn on fast user switching to let more than one user stay logged in to the computer at the same time, and you can switch between users by choosing from a menu.
Turn on fast user switching
- Choose Apple menu > System Preferences, and then click Users & Groups.
- Click the lock icon to unlock it, and then enter an administrator name and password.
- Click Login Options.
- Select “Show fast user switching menu as,” and then choose an option from the pop-up menu.