I have an external monitor connected to my MBP via HDMI. I can use my laptop in 'clamshell' mode, where I close the laptop's lid and work off of my external monitor.

The problem I have is that when I open the laptop's lid some of my windows move off the external monitor to the laptop. Some trial and error shows that if a window is on the laptop when I close the lid, that window will reappear on the laptop if I reopen the lid, even if I move the window around while it is on the external monitor.

How can I prevent my mac from moving windows to the laptop. I want all windows to stay on the external monitor until I physically move them to the laptop, and once I close the lid they should stay on the external monitor even if I re-open the lid.

1 Answer 1


Welcome to Ask Different. I think your experimentation has you on the right track. If you drag a window to the external monitor before closing the lid on your laptop, it should stay on the external monitor after opening the lid again. You may also want to check which monitor you have as primary - that's where your desktop icons will first appear. In System Preferences, go to Displays and then click on the Arrangement tab. The display with the white bar on top is primary. You can drag that bar to the other display to make it primary.

  • Thanks for the primary monitor tip, I didn't know about that. So I guess there is no way to make it so that when I open the lid no windows show up on it?
    – totsubo
    Sep 17, 2020 at 21:22
  • If you move all windows from the laptop screen to the second monitor before closing the lid, they will all stay on the second monitor when you open the lid. Give it a try.
    – bitfiddler
    Sep 17, 2020 at 22:05
  • I understood that part :) I meant to say, is there a setting that prevents windows from moving? In other words it doesn't matter where the windows was when I closed the lid, it will stay on the external monitor (my primary) when I open the lid? I don't want to need to move all open windows over to the external monitor every time I close the lid.
    – totsubo
    Sep 18, 2020 at 2:22
  • Switching the external monitor to primary will allow you to launch apps from there, since the desktop icon and dock will be there. So they will stay there unless you move them. If that doesn't get you there, take a look at the app mentioned in one of the answers to this older question here: Can I prevent OS X from resizing and moving windows when sleeping while attached to an external monitor?
    – bitfiddler
    Sep 18, 2020 at 15:58

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