Why is it no longer possible to adjust the properties for Windows Defender?

DaveKoe 20 Reputation points
2026-08-03T18:01:49.7433333+00:00

I previously could go into the Task Scheduler and change the properties for Windows Defender to keep it from running with the highest privileges and to set a Trigger time daily. Now when I make these changes, they do not stick. Meaning they seem to save, but when I go back in, the changes are gone.
Antimalware service executable often renders my PC unusable as my programs stall and freeze.

Processor 12th Gen Intel(R) Core(TM) i7-1260P (2.10 GHz)
Installed RAM 16.0 GB (15.7 GB usable)
Graphics card Intel(R) Iris(R) Xe Graphics (128 MB)
System type 64-bit operating system, x64-based processor

Microsoft 365 and Office | Microsoft 365 Defender | For home | Windows
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Answer accepted by question author
Allan Solomon Mejia 8,585 Reputation points
2026-08-03T20:44:50.9833333+00:00

Hello @DaveKoe

What you're seeing is expected behavior in recent versions of Windows.

Many Microsoft Defender Antivirus scheduled tasks are protected by Windows Resource Protection (WRP) and Tamper Protection. Even if you modify task properties in Task Scheduler, Windows may automatically restore the default configuration, which is why your changes appear to save initially but are reverted later.

If the Antimalware Service Executable (MsMpEng.exe) is causing excessive CPU or disk usage, I would recommend investigating the root cause rather than modifying the scheduled task:

  • Ensure Windows and Microsoft Defender signatures are fully up to date.
  • Check whether a full scan is running or repeatedly restarting.
  • Add exclusions only for trusted folders or processes that Microsoft recommends excluding (for example, certain development tools or virtual machine directories), rather than disabling protection.
  • Review Task Manager and Resource Monitor to identify whether another process is triggering continuous Defender scanning.
  • Verify that no third-party antivirus or security software is conflicting with Microsoft Defender.

Since your system has 16 GB of RAM and a 12th Gen Intel Core i7, it shouldn't normally become unusable during routine Defender scans. If the freezes are persistent, reviewing the Microsoft-Windows-Windows Defender/Operational log in Event Viewer may help identify repeated scans, errors, or other abnormal behavior.

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