Set screen blanking time
To save power, you can adjust the time before the screen blanks when left idle. You can also disable the blanking completely.
To set the screen blanking time:
Open the Activities overview and start typing Power.
Click Power to open the panel.
Use the Screen Blank drop-down list under Power Saving Options to set the time until the screen blanks, or disable the blanking completely.
When your computer is left idle, the screen will automatically lock itself for security reasons. To change this behavior, see.