Currently the MacBook's display works as primary, so every application I open gets open on the 13" and I have to drag it to the 24". I also don't have access to the dock on my 24".

Is is possible to turn off the MacBook screen and use only the one attached via DVI?

(I've just connected my 24" HP LP2475w via Mini DisplayPort to DVI to my MacBook Pro 13", which works great except for this one thing.)

  • After a few search, it might be a duplicate. I'll let the mod decide. apple.stackexchange.com/q/3697 Jan 10, 2011 at 12:56
  • Not a dupe IMO.
    – user588
    Jan 10, 2011 at 15:50
  • I suggest breaking this up into two questions, as you can tell you're having to repeat one in the comments to an answer below...
    – user588
    Jan 10, 2011 at 15:52
  • @LoïcWolff Nope. Not a dup, as the question here is about the default position of an application.
    – daviesgeek
    Aug 16, 2012 at 7:04

7 Answers 7


Under your System Preferences > Display, you've got this alt text

Just drag the white bar to the other screen to set it as the main screen.

You might have to do that every time you reboot / reconnect the external screen.

  • Works great, thanks. Is there any way I can turn off the MacBook screen off? I have connected my Magic Mouse and external keyboard, but when I close the lid, it just puts the system to sleep. Jan 10, 2011 at 13:00
  • 1
    @Darth Did you try to set the luminosity of the screen to a minimum? It doesn't affect the external screen and the lowest setting is pretty much black. Jan 10, 2011 at 13:02
  • That works great, as the lowest luminosity turns the screen off. The only problem I see now is that it seems a little laggy, not sure if that's normal or because the laptop screen is still on. Jan 10, 2011 at 14:33
  • @Darth what seems laggy? The whole computer? It didn't happened when the main screen was the macbook? Jan 10, 2011 at 14:50
  • @Darth it doesn't actually turn the screen off. Try decreasing the luminosity and then expose the screen to bright light with something on it, like a window or a webpage. You can still see the contents of the screen, it's just the backlight that is off.
    – bisko
    Sep 25, 2011 at 10:16

Loïc answered for the main monitor question. For closing the lid of your MacBook, it's what is called to use it in clamshell mode. As you will have to have an external mouse and keyboard connected to your laptop, you have to boot, close your lid (your mac will turn to sleep) and then use your mouse or keyboard to wake it from sleep mode.

If you have a bluetooth mouse and/or keyboard, you have to go in the bluetooth prefpane, and, in Advanced settings, check the Allow Bluetooth devices to wake this computer.

By the way, in this situation, no need anymore for a main and secondary monitor :)

When you open your lid while using only the external monitor, the macbook screen will stay black. If you want to use again both screens, you have to go to the Displays prefpane and click on Detect displays. Or, like me, check the Show displays in menu barand use the menubar instead to detect the displays.


While running a dual-display setup, you can easily adjust the primary display monitor in Mac OS X. Before beginning, have both displays turned on, and the external display already connected to the Mac:

  1. Go to System Preferences -> Displays
  2. Choose the ‘Arrangement’ tab
  3. Click and hold on the white bar at the top of the current primary display
  4. Drag the white bar across to the other monitor you want to set as the new primary display
  5. After you release the white bar, both screens will flicker briefly and adjust to accommodate new settings

enter image description here

Whatever monitor is set as primary it will become the default display for applications launching, in addition to holding the system menubar, containing all the default desktop icons and the Dock.

Note that if the secondary display will be detached, the primary screen will revert back to a built-in display on any portable Mac.

Here is the link to the original post about it.

  • 1
    it's usually a good idea to put solution here AND provide a link to where you've found it. We do this because linked pages can get expired or deleted. Jan 23, 2016 at 2:39
  • @ranklord, good point, I just update my answer.
    Jan 23, 2016 at 2:48
  • I'm a bit confused as to why you answer a 5 year old question which already has an accepted answer, with the same solution as yours, and 34 votes. Jan 23, 2016 at 13:12


Secondbar adds a second menu bar http://www.macupdate.com/app/mac/33264/secondbar


Want o work on your external monitor while mac latop lid is closed? Plug your laptop your charger and close the lid and it will not sleep. Thats the trick

  • This is not what the OP is asking about. There is another question on here about what you described. However, keep in mind that it is the Display Out that needs to be plugged in, not the power cord. Feb 28, 2013 at 13:20

For me with just two screens. The above mentioned solutions didn't work as the new apps would open in the laptop itself. What worked is moving dock to right. Dock to right

Also I had to do this https://discussions.apple.com/thread/251274566

  1. Go to mission control
  2. Add a new desktop
  3. Right click on the app in dock
  4. Delect options and select the display

select display from doc


MBP 13" Oct 2010 Plug in external monitor and close the mbp's lid

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