Instead of doing what I did, which was installing, deleting and then re-installing the game, you can try to adjust your control panel settings in order to glean some entertainment out of a pretty good game. just look at it as a horribly inconvenient way to change advanced graphics settings.

Find your NVIDIA control panel through searching, right clicking the executable or finding the program in your taskbar.

Go to "3d Settings -> Manage 3d settings"
Go to the "Program Settings" tab and select the executable for your copy of DOA6, you may have to add it.
The typical executable location is in your "steam" folder, in steamapps->common

Some of the settings I adjusted for myself were:

Antialiasing: FXAA : off
Antialiasing Gamma : off
Antialissing Mode : off

Low Latency - Ultra
and Max Frame Rate - 58 FPS

I don't know your hardware or settings, but for me this maintained the model shadow quality of the characters and greatly improved the rendering. This may help some people with the games settings being disregarded during online play.

I have an NVIDIA GPU and do not use geforce experience, but the same concept may apply for users of other GPU control panels for setting specific settings onto the game which otherwise may be unavailable.