Laptop External Monitor having trouble displaying games?

[siberiansteel11]

So recently I purchased my first gaming laptop. the MSI leopard pro it's pretty good has a gtx 960m, i7 6700hq basically runs game at decent framerates. so I tried hooking up an old monitor, this monitor has a resolution of 1366x768  and only has a vga port. I made the monitor my primary via windows options. my goal was to run games at 1366x768 and see the framerate difference. the first game I tested was witcher 3. now I already set witcher 3 at 1366x768 using nvidia geforce experience. The problem is when I open witcher 3 the external monitor doesn't show it. it only gives the error " Input error display". so what I did was I made my laptop's monitor primary again and voila the game opened at 1366x768. so what I did was I made it into 1280x720 and made run it at window mode, then drag the game to the external monitor. then what I did was make the external monitor the primary one again and made witcher 3 run at borderless window mode. then it worked! so my question is any solution for this input error display? cos doing this whole procedure is a bit of a nuisance.