Question [Question] Why does the display switch to the TV when someone turns it on?

[Bat123Man]

I have Win10 set up with an LG widescreen monitor via HDMI, connected to a 6GB 1060 GTX. I ran a second HDMI cable through the joists in the ceiling to emerge behind the TV, and it is connected to an LG SoundBar, which in turn is connected via HDMI to the TV. Everything works. I can use the Windows + P dual screen control to change output from the monitor to the TV by selecting "Second Screen Only". As long as the Sharp Roku TV is set to Computer, the output shows up on the TV. However, if someone is using the computer with the monitor, and someone else comes along and turns on the TV, the display switches automatically to the TV. It isn't Extended or Duplicated, the monitor goes black and the TV becomes the only output. I can easily switch it back via Windows + P, but it must somehow think that is desired behaviour. Does anyone know how to turn it off?

The only thing I can think of is when I go into Display settings, the monitor is listed as Display 2, whereas the TV is listed as Display 1. I am not sure if that makes a difference, but I can't figure out how to swap them. Display 2 (monitor) is listed as Default and Windows + P switches to it when I select "PC Screen Only". My son is so frustrated by this behaviour that he has started to regularly unplug the SoundBar so that his younger brother doesn't come along and turn on the TV while he is playing Skyrim on the computer. Obviously Win10 is correctly detecting that a second monitor has been made available, but how do I prevent Windows from automatically switching to that display?

Thanks,
BM.

 

[VirtualLarry]

Since Windows supported HDMI, it tends to "prefer" it. I don't know if there are any registry entries to change this behavior or not. I guess it was put in at the behest of HTPC aficionados, but it has lingered on a little too long.

 

[OlyAR15]

In the nvidia control panel, you should be able to set which monitor is the primary display. Maybe that might help.

 

[Bat123Man]

OK, thanks. I figured out how to use the option "Make this my main display" which deserves an entry in the sub-reddit /r/CrappyDesign. You actually have to select one of the two blue rectangles at the top of that page, and then scroll down to the very bottom of that page where that option will have magically un-greyed itself. Why MS didn't choose to put that option directly underneath the Display window with the blue rectangles is beyond me. At any rate, I have ensured the monitor is the main display. It is still listed as Display: 2, but in my mind that should not matter as long as it is considered the main display.

I have not been able to reproduce the issue since ensuring it was the main display, but I'll see if it passes the kid test over the next few days. Thanks for the replies.