U3415W, problems with eyestrain and PBP

I invested in this very expensive monitor months ago and am not happy with it.

Coming from a dual screen setup I had used for more than 10 years I have experienced much eyestrain and worsening of my sight (!) since using this monitor.

After experimenting I found that the least bas settings are having the monitor at 5000K, 44% brightness and 59% contrast, but it is still much worse than my dual screen setup. I had to put the text at 125% to be able to read anything at all.

Does anyone know better settings which I haven't found yet?

Second problem, I have connected a second cable to enjoy a "dual screen" setup in PBP full mode. I needed to install the NVidia manager to get this to properly work, without it the monitor showed 2 very narrow screens with large black bands next to them.

The settings of the "second" (PBP) screen can not be changed apparently which is very annoying: both screens have different display settings. The dell display manager shows 2 U3415W monitors, but changing either of them only changed the settings of the "main" screen, the PBP screen remains unchanged.

How can I syncronize them?