In-game HDR settings for LG C9?

[Rushnerd]

I'm sure not many of you are playing this on an LG C9 or CX display, but i'm finding the HDR settings confusing and wondered if anyone has it figured out better than I have.
The paper white value is most what i'm not sure what to set at and if I should even be messing with the "HDR brightness" slider.

[{MoO}Tanquen]

I have my LG77C9 set at 700 and it seems ok.

I do see that the black level floor changes randomly. Sometimes when I start the game the first logos are on a completely black screen. Other times it's a little grey.

[Ellis_Cake]

I wish the win10 HDR setting was out of the picture cus i feel it complicates