[This version of Windows Defender is still in development, so some Help information might be inaccurate or missing.]

Turn real-time spyware protection on or off

To complete these steps, you must be logged on as Administrator or be a member of the Administrators group.

To help prevent spyware and other unwanted software from infecting your computer, turn on Windows Defender real-time protection and select all real-time protection options. Real-time protection alerts you when spyware and other potentially unwanted software attempts to install itself or run on your computer. You are also alerted if programs attempt to change important Windows settings.

To turn real-time protection on or off

Open Windows Defender. (Click Start, click Programs, and then click Windows Defender.)
Click Tools, and then click General Settings.
Under Real-time protection options, select the Turn on real-time protection (recommended) check box.
Select the options that you want. To help protect your privacy and your computer, we recommend that you select all real-time protection options.
Under Choose when Windows Defender should notify you, select the options you want, and then click Save.