Mac OS X 10.1.5: Video Mirroring Setting Changes After Upgrading

After updating to Mac OS X version 10.1.5, video mirroring may be disabled and extended desktop may be enabled. If necessary, re-enable video mirroring using the Displays pane of System Preferences.
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Symptom

After updating to Mac OS X on a computer with an additional display connected, extended desktop is enabled instead of video mirroring.


Solution

Use the Displays preference pane to re-enable mirroring:
    1. Open System Preferences from the Apple menu.
    2. Choose Displays from the View menu.
    3. Click the Arrange tab.
    4. Select Mirror Displays.
    5. Quit System Preferences.
Published Date: Oct 10, 2016