When you leave your computer, it’s best to start a screen saver that can only be turned off with a password. You should set up a screen saver that will start after your computer has been idle for a set interval (15 minutes or less). 

You can also lock your screen manually.

How to Set Your Computer to Lock Your Screen Automatically

When you leave your computer, it’s best to start a screensaver that can only be turned off with a password.

In Windows 10:

1. Click the Start menu, then Control Panel (gear icon).
2. Click Personalization, then Lock Screen.
3. Optionally, choose a Background option from the dropdown list
4. Optionally, choose apps that will display status information while the screen is locked (for example, Alarms and Clock or Weather). Click a square with a plus in the middle and then click one of the Windows apps from the pop-up list to add it. To stop showing an app on the computer's lock screen, click its icon, then choose None from the pop-up list.
5. Optionally, click Show lock screen background picture on the sign-in screen.
6. Click Screen timeout settings, then selecting values from the Screen and Sleep dropdown lists to set how long it takes for your screen to lock or go to sleep.

When your computer has been inactive for the set amount of time, the screen saver starts. Your password is required to start using the computer again.

How to Lock Your Screen Manually

Use this procedure to lock your screen without waiting for the screen saver to start. It is recommended to do this whenever leaving your computer unattended.

1. Press the Windows logo key + L.
2. Click the mouse or touch any key to show the sign-in screen.
3. Sign back in using your password (on managed computers, this will be your Cornell password).