If you did a clean install of Windows, Microsoft Defender should be enabled by default with real-time protection turned on. But if your computer came with a trial version of an antivirus, then chances are it’s disabled. If you don’t plan on paying for it once it expires, and it’s your personal computer, you should uninstall it and use Windows Security instead. It’s built-in and 100% free.

The most important thing you need to do in Windows Security is ensure the built-in antivirus, Microsoft Defender, is running. Go to Settings > Privacy & Security > Windows Security and click the “Open Windows Security” button. Next, select “Virus & Threat Protection” in the left-side menu, and then click “Manage Settings” link under Virus & Threat Protection Settings.

Ensure that the “Real-Time Protection” toggle is turned on.

Afterward, you can look into other Windows Security settings, such as the Firewall, App & Browser Control, and Device Security.