Running El Capitan, I have two external monitors and the MBP monitor, three total. When the MBP is not hooked to any monitors, I have four Spaces set up, each with their own desktop background (A, B, C & D). When the external monitors are hooked up, I get two more spaces ("Displays have separate Spaces" is checked) with two more background pictures (E & F). I arrange them in a V:

Ext1 -- Ext2
  \\    //

The top left monitor becomes my main display (Desktop #1) and has the four spaces. I don't know why it does this but it does, and that's what I want, too. So it has desktop backgrounds A-D. Top right gets picture E (Desktop #2), and the MBP gets picture F (Desktop #3).

This is exactly what I want, as A & E complement one another. Except sometimes (maybe 3% of the time) the MBP becomes Desktop #2 and gets background E and the upper right becomes Desktop #3 and gets background F, which is just visually jarring to me.

When it happens, everything is still arranged in the V that I want, so it's not like the OS is confusing what's what.

Q: Why does this happen or how can I fix it?

  • Have a look at this answer
    – Allan
    Commented Mar 4, 2017 at 14:57
  • It's a work laptop, so I can't install third party software on it. Commented Mar 4, 2017 at 14:59
  • Poked around and googled, both without success. There's very little in the way of settings that I can find to affect this. Commented Mar 8, 2017 at 23:21
  • I am using an app called TotalSpaces2 that can mess with the spaces. Maybe it can do what you want, or you could contact the devs and see if they can help. Commented Mar 10, 2017 at 10:51


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