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Those who perform a clean install like myself do not have the Windows Defender Registry value in the Run section, so they also have no tray icon. The "-hide" switch is preventing the tray icon from being visible, so those users never see it! However, for many users the Windows Defender line in the Registry looks like this: "%ProgramFiles%\Windows Defender\MSASCui.exe" -hide -runkey Some previously released builds of Windows 10 had the appropriate value in the Registry in the Run key. In Windows 10, those Windows Insiders who are installing new builds via Windows Update often have the Defender tray icon visible. Why some users have Windows Defender tray icon enabled by default and others not Again, delete all values which point to the file "Program Files\Windows Defender\MSASCui.exe".Tip: You can switch between HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE subkeys quickly using the new feature of the Registry Editor in Windows 10 as described here: Windows 10 updates the Registry Editor. Now, go to the following Registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run.Delete all values which point to the file "Program Files\Windows Defender\MSASCui.exe".To hide the Windows Defender tray icon in Windows 10, you need to do the following: How to hide Windows Defender tray icon in Windows 10 Reboot Windows 10 or sign out and login back to your user account.Set to the following value: "%ProgramFiles%\Windows Defender\MSASCui.exe"-runkey
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Here create a new string value named "Windows Defender".Tip: You can access any desired Registry key with one click. Go to the following Registry key: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run.Why some users have Windows Defender tray icon enabled by default and others not How to show Windows Defender tray icon in Windows 10
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