Multiple screens of different dpi show blurry text (really bad)

my setup:
win10 with 3 monitors: 4k 27" monitor and two 24" 1920x1080 monitors.
windows suggested 150% dpi for the 4k and 100% for the others.
4k looks great but the 24" (with 100% dpi!) looks terrible. The text is all blurry.
I saw many similar issues (saw this: https://www.tenforums.com/general-dis...ry-text-4.html)
and tried the registry changes, but all fixes (including the utility that is out there) set all monitors to the same DPI.
I can't do 100% in the 4k, it's too small, and I must do 100% in the small screens, otherwise it's too big.
Got latest drivers for my GeForce GTX 970 and monitors (vendors drivers for all monitors).

I really don't want to let go of my 4k, but it is impossible to use the other ones.
I attached an example for when the 4k is d/c (top) and when it is connected (bottom) from the 24" monitor. it is not really text but is shows how terrible it is, I simply can't read for more than a few minutes.



Please help!

Thanks,
Roy.