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.
Open Windows Defender by clicking the Start button , clicking All Programs, and then clicking Windows Defender.
Click Tools, and then click Options.
Under Real-time protection options, select the Use real-time protection (recommended) check box.
Select the options you want. To help protect your privacy and your computer, we recommend that you select all real-time protection options.
Under Choose if Windows Defender should notify you about, select the options you want, and then click Save.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.