How to get your external monitor to show a different desktop.

When you plug in a second monitor to Macintosh computer, it may display an exact copy or ‘mirror image’ of what is on your first display.  This is called mirroring.  This is fine if you are doing a presentation and you want to see on your laptop screen exactly what is on the projector,  but it’s not very useful at home to have the same thing on both screens. If you’d like to see different things on each screen, so the second screen gives you more desktop space, you need to turn mirroring off. Here’s how.

1.Go to’ system preferences’  in the Apple menu,  and then to ‘ displays’  and  click on the ‘arrangement’  tab.


2. Deselect the box that says ‘ Mirror Displays’


3. You have now turned off mirroring and should have two separate desktops!


On some machines,  for example lower end of iBooks and iMacs,   to differentiate them from the higher models, Apple have disabled the ability to have two separate displays so that your external monitor is permanently mirroring what is on your main monitor.

There is a program that can re-enable this feature to turn on the ability to have a separate second display.  It’s  called  screen spanning doctor. It automatically checks that your Mac is able to run a second monitor and then makes the appropriate changes. You can download it from here.


15 responses to “How to get your external monitor to show a different desktop.”

  1. Eldreda Christner

    I am amazed with it.It is good thing for my research. Thanks. ^_^

  2. Zoe

    How do i make the external monitor my main screen so that when for example, photoshop is open, i don’t have to go back to the MBP to access the top menu bar like File, Edit, etc… With my set up the MBP is on the left, my new 24″ is on the right. I am able to align the dock to the right and it shows up on the right hand side of the 24″ screen. But the menu bar for all applications is back on the MBP.

  3. Zack

    It real simple, just open up “system preferences” and the click on “displays” it should show your two displays, one of the displays will show a little menu bar, now just click and drag the bar to whatever window you’d like it in.

  4. Tom

    How to get my external monitor to show a different screen powerpoint presentation in window based laptop

  5. Stephanie

    I have external monitor connected to my macbook pro and am using extended desktop. Because of physical desktop space limitations, the external monitor has to sit to the left of my laptop. However, my mac extends the desktop to the right of the screen. So I have to run the mouse off to the right on the laptop screen to get to the external monitor on the left. I didn’t see anywhere in the displays settings to change this, like you would on a computer running Windows. Advice? Thanks!

  6. Hey Stephanie, in classic mac UI fashion, the simplest answer is usually the right one. Go to “System Preferences”, click on “Displays”, click “Arrangement” and simply drag the display icons to the configuration you need.

  7. Alessandra

    hey I tried to download, this screen scanning software but it doesn’t open. I have the latest Mac Book Pro 15″ and I just can’t detect other displays. I don’t even have “arrangements” on my display menu! can someone help? thanks!

  8. Mared

    i’ve just purchased a connector to my macbook pro and tv and the arrangement tab does not appear in the display setting! any help?

    1. Matt

      I have the very same problem Mared.

      I have a macbook pro thats only about a year old. I have a moshi connector plugged to my macbook and an HDMI cable going from that to the HDTV. Nothing happens because when I go to the display setting it will NOT give me the option to even click on arrangement. It’s not ever there. Why is this????? Please someone help

      1. might be better off buying an apple adapter – moshi have problems maybe? Is the output working to the TV?

  9. Speaksy

    Thank you for this post! It’s very helpful and I went ahead and got myself a portable monitor.

    GeChic 1303H, is a 13.3″ portable monitor which I use connected to my MacBook. I didn’t have any trouble with connections and there were no driver installations.

    I’ve only used it for a week with my Macbook Pro so I can’t comment too much as of yet. It comes with an HDMI cable so you can hook it up to your mac mini as well. I’ve listed some of the highlights of the monitor below:

    – Great picture quality/resolution; I’ve only tried web browsing and PS4 games so far but the monitor displays an an awesome 1080p picture with a clean refresh rate. Great colour range as well. You can make the picture very vibrant if needed.
    – Easy to set up and use; can theoretically plug any device with visual output into this thing if you have the right adaptors/cables.
    – Thin and light; this monitor is as thin as an iPhone 4
    – Useful case/stand
    – Simple menu navigation for settings

    I’ve had so much fun with this product I thought I’d share with other people as well!

  10. Ben

    Quick question. My desktop background on my macbook is different from the one on the monitor when i plug my hdmi cord in. How do i get them to match without them seeing my actual desktop?

    1. Go to system preferences and set the background from there under desktop settings.

  11. Ethan

    Is there any way that I can get my full screened video playing on the second monitor while I’m on desktop 1 on my MacBook?

  12. Cristian

    I run an extended display on a secondary monitor. However, I also use my secondary monitor for multiple devices. Is there a way I can have my primary display show me what is on my secondary display without having to change my secondary display’s input (which is much more complicated than it should be). I’ve tried mission control but this wants to show me how to create a secondary desktop and all I want is to see what is on my extended display. Thanks.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.