Windows 10 Multiple 4K Displays - All Windows Move To Primary Monitor On Resume BUT ONLY When Text Scaling Not Set To 100%

The problem you are seeing is a "Feature" of Windows introduced a good while back without a way to effectively turn it off. Certain monitors (Especially TVs) when in sleep or off will report (lack of report) back to the PC that they are, in fact, off/disconnected. Windows then does it's "feature" of moving all applications from the 'disconnected' screen to a connected and running monitor. It will move everything to your primary unless the primary itself is "disconnected".

Solution(s)

1 Manual Mode:

Turn your PC off when done at night, then your monitors off afterwards. In the morning, do the reverse and turn on monitors first and while they are in their 'no source found' error, hope your PC boots up in time before they sleep.

[For your laptop'sake] Your laptop will boot to it's primary screen and not output to the secondary monitors until after booting. So their wake cycle may be too slow between when windows starts to load and sends a zappy zap (technical term) to begin their wake process, and when windows is fully loaded and the "feature" kicks in of moving apps to the online screen.

[For others with PCs looking at this] Problem is many Bios will only output on 2 of say 4 screen thus allowing 2 to go to sleep anyways. If windows boots before those 2 sleep, you are good. if it boots while they are asleep/ "disconnected" your apps will be moved.

2 Third Party Software

While I personally haven't used it, this third party program is cited in several places around Microsoft technet to be able to force/solve this issue. It allows one to make a profile for apps to open on a specific monitor every time.. So their's that..

https://www.actualtools.com/multiplemonitors/features/multi_monitor_window_management/

3 100% Windows scaled 150% forced scale

No Idea how to title this. I do it for my monitor sometimes, but you could do a 150% scaling through NVidia with custom resolution. To Windows, you are keeping it at 100% scaling. The graphics card itself does the 150% scaling by taking an input of 2304x1269 and outputting to the screen a 3840x2160 resolution. I have outlined it below in this screenshot..

Side note

I deal with these issues regularly as the IT guy for an AV integration company. Not all monitors talk to the PC while the screen is off and thus the most hated anti-productivity 'feature' will ruin your day. Above is all I have to offer, I got to the point where I tossed my monitors which appear off to windows while waking to the test bench and now have some dell monitors that always report 'connected' when in sleep or wake mode.

Antony T.

Posted 2020-01-30T20:26:49.377

Reputation: 143

You don't even have to put the computer to sleep to trigger this "feature". Simply turning off the secondary monitor before the primary can move all of your windows to the primary. Locking the PC also shows a full-black picture on the secondary monitor; Which can cause many monitors to turn off or go to sleep automatically! – Romen – 2020-01-30T21:01:11.943

Thanks for your answer. Unfortunately this is a misdiagnosis.

As I stated in my question, the monitors work perfectly as expected and do not exhibit the behaviours you described when the display scaling is set to 100%, and of course the previous setup with 3 x 1080p monitors also worked perfectly. Furthermore, when turning either monitor off in turn does not cause the windows to move. – James Law – 2020-01-30T21:11:49.770

@JamesLaw I remembered a 3rd method that I actually use on my work PC. I have added it in and I'm pretty sure it would fix your issues from what you have just said. – Antony T. – 2020-01-31T19:17:07.670

Windows 10 Multiple 4K Displays - All Windows Move To Primary Monitor On Resume BUT ONLY When Text Scaling Not Set To 100%

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