Yeah, it's not a wide gamut screen.
I've just been playing with my NEC, but the controls aren't quite the same.
If you go up one step to get to "WHITE", can you then use the left and right arrows to adjust the white temp?
It is related to resolution and quality of course, but by itself the jpeg file size is not a firm indicator of those things.
You need to explain to her that smaller jpeg size is actually an indication of better file quality.
https://www.damiensymonds.net/2015/08/about-jpeg-file-size.html