Using Windows 10, i have 2 screens connected to my "GeForce GTX 660":
1. Samsung S23B350 Screen connected via a DVI Cable.
2. SHARP HDMI TV connected via a HDMI Cable.
Obviously i want the Samsung screen to be my main display, and thus i made it my main display both on my Windows 10 Display Settings and my NVIDIA control panel:
The problem starts when i want only my PC (Samsung) Monitor to display,
changing to "PC Screen Only" using WIN+P will turn off my Samsung screen and display my desktop only on my HDMI Screen.
(When i choose "Second Screen Only" it does what i want to happen in the previous situation)
If i'll press "Identify" in the Windows Display Settings to see which is my Samsung screen and than choose "Show only on X" in the "Multiple displays" drop down it will work fine.
I tried everything and looked everywhere and i can't find the solution,
i know it might be a minor issue but it's bugging me a lot when i accidentally choose the "wrong" option etc.
Best Answer
I had the same problem after replacing a projector in my 3 screen setup. What worked for me was a much simpler fix.
SOLUTION
This solved the problem for me. I hope it helps others!
TL;DR Go through windows+P menu 1 by 1, setting up and applying the correct display config for each in Nvidia control panel.