Trying to scale one monitor, but it's scaling all of them, help!

So I just got a 4k monitor to add to my two 1080p monitors. I set everything up and it was all fine and good for an hour or so. Basically what's happening is the scale option is locked to the primary display. If I increase the scale of one, the rest follow suit. I've been trying to fix this for hours and need to get this in order so I can work, so please help!

If it helps, I have an Nvidia GTX 970 and the monitors are two HP 2511's (1DVi/1 HDMI) and a Samsung U28E590D 4k monitor, running through a DisplayPort.

The goal here is to have the 4k at 150% scale and the other two at 100%.

Thanks!

I had the same issue but with a different 4K setup , but ended up returning it for a Benq 3200pt instead which has no issue doing what you suggested with my 970 .

Only thing I can think of it that the monitor maybe in AV (TV) instead of PC mode

I think it's related to the running app

I used to do the same thing for my (previous) dual monitor setup with extended desktop, with one 1080p (125%) and another to 1366x768 (100%) and in some apps, the window appeared too big on the 1366x768 because was scaled to 125.