I have a Lenovo 580T, Windows 10.1903; with an attached second monitor, Dell 2311H, which I had also used for my T530 running Win7.

Of course I am having display issues, probably because of Win10's DPI Scaling policy. The recommended scaling is 125% for the original screen, and the scaling is set at 100% for the second screen. The second monitor renders fine enough, if not a tiny bit blurrier than on the Win7 machine, but certain legacy apps I run appear blurry on my main (laptop) screen:

Can I Decouple Two Monitors' Display Settings?-fileback-old.jpg

Can I Decouple Two Monitors' Display Settings?-chrome-old.jpg

I found a web page online that recommends how to fix this: apply custom scaling of 125, same as the "recommended" default scaling, sign out and sign back in, and voila, your blurriness will be fixed without changing anything else.

Except not so voila. The legacy app does appear very sharp and at mostly the same size as before, but now the scaling on the second screen is freakishly big:

Can I Decouple Two Monitors' Display Settings?-fileback-new.jpg

Can I Decouple Two Monitors' Display Settings?-chrome-new.jpg

When I open display setting to see the result of my fix, the scaling is grayed out and set to 175% for both monitors, not the 125% I chose. I tried as much as I could to decouple the scaling for the laptop monitor and the second monitor, but I can't figure out how to make it stick or render properly.

I did go to device manager to check drivers and did successfully update the Generic PnP monitor driver to the specific Dell 2311H driver, but that did not help. The issue appears in native Display settings, and my inability to decouple the monitors through them.

Unless I am missing something? Can anyone suggest a fix for this?