windows/applications are moving to different monitors

Hi, i’m having an issue where windows/applications are moving to different monitors, Could you please help?



I have 3 monitors, an iMac screen, a 4k tv, and an HP 1080 monitor that about 25”. I generally always keep my applications in the same place… I keep firefox (playing youtube) on the HP monitor and I keep a few applications that i use often (Ableton Live, Astropad, Resolume Avenue, and others) in the same place on the bottom left corner of the 4k TV.

However, these applications frequently move to other monitors (or different locations on the same monitor) automatically when i’m not looking. I never notice it happening as i’m using the computer, but it happens often when I come back to the computer after a break. I’m not sure if it happens 100% of the time, but it happens at least a couple times a day. It usually moves the windows in the same way- it moves Firefox to the 4k tv, it move Resolume avenue down to the bottom of the HP monitor (where its barely visible), it moves Ableton to the iMac screen, Astropad either moves to the middle of the TV or to the imac screen...


I’m thinking that it might have something to do with monitors disconnecting because the power is shut off… When i take a break and leave the room, I usually put the monitors displays to ‘display sleep’ (not actual sleep), turn the power off on my surge protectors which connect to my usb hubs (which isn’t connected to the monitors at all), and I sometimes turn the power off of 4k tv separately too. Could the powering off of the TV or display sleep be messing it up?

Also thinking that it could be some software setting or application causing it, not sure. Or is there something else?


Why is this happening? And how do i stop the windows from moving automatically?


Thanks!




(iMac 5k 2015, ) MacOSx 10.13.6 (17G65)

Try not turning the displays off, this should fix the issue? If the computer is on, and the monitors are not powered on, then the computer, thinks they are not being used anymore.

Edit: Maybe, if you power the tv/monitor back on before you "activate" your iMac, it may see the displays as still there and put everything back where it belongs?

+1 for what Bob said. If you power off a display, the Mac thinks it's been detached (in a sense, it has been electronically detached). And the display tries to rearrange the windows on the remaining displays, which to you looks like they are moving around. You need to keep external monitors powered on to the point where they don't "disappear" from the Mac. It's probably OK if they "sleep" as long as power is still on and the monitor responds to the Mac to "wake up" from the sleep when the Mac wakes up.

Gentlemen I think you have probably cracked it. I've got an external monitor attached to my Late 2915 iMac and sometimes it exhibits the behavior the OP has noticed. Happens to me every once in a while but I;ve never bothered to chase down the problem. Couldn't figure it out vut I think you are right. Tjat never crossed my mind when I read this thread earlier.

At this rate Charlie will be sending me an extra large dunce cap instead of a ten gallon genius hat. lol

Sly, I only know about it because I have an external monitor and if I power it off all of the windows on it get rearranged onto my MBP screen. I figure the same thing is happening to danklim.

I have essentially the same situation happening. In my case it's an external monitor connected to a an iMac. I just had never made the connection that it was the monitor being off that was causing the problem.

Hmmm ok thanks everyone!

I've just tested it and see that when the displays are turned off and the 4k tv monitor is turned off, the firefox window always moves to the that 4k tv monitor when sleep is awakened. Not sure whats going on with the other apps yet, will test it more.


Also remembered/realized that i've only been having this issue since i got the 4k tv monitor. This TV monitor doesn't work the same way as my HP monitor- when i turn display sleep on, the HP monitor the HP monitor goes black just like my imac screen. But the TV monitor goes black for a second then shows a screen saying that no HDMI input it selected. I don't want to leave this on bc i dont want to burn the screen out or waste power, so i usually either manually turn it off or allow the automatic power down/sleep setting to turn if off after 15 minutes. However, both of these actions are causing the windows to move. I haven't been able to find any other settings on the TV to fix it or let the screen go black while not causing the windows to move, are there any ways i can fix this? Or any best practices to use when using TV's as monitors to avoid this?

The windows shift when you power it off. Sleeping, the "no HDMI" message should eventually go away, but it will stay in touch with the Mac. If you can't set it to stay on, but blacked out, you really don't have many options. You could, I suppose, just before sleeping the Mac move all the windows where you want them to be NOT on the TV, but that's a real PITA. You might test to see if the windows move around if you just let the 15 minute timer elapse and the TV go into deeper sleep. Typically, if it can be turned on with a remote, it's not really OFF, just sleeping.

In the “Arrangement” window, is the TV the second or third display? Does changing the arrangement help?