If you are having trouble with the visibility of the A-10C hud you can
try changing the hud color.
The color is specified in a file located here (your hard drive letter may differ):
"D:\DCS World 2 OpenAlpha\Mods\aircraft\A-10C\Cockpit\Scripts\HUD\Indicator\HUD_init.lua"
You can edit this file with any text editor. Scroll down to the last two lines:
day_color = {0, 255/255, 0, 255/255}
night_color = {243/255, 116/255, 13/255, 255/255}
The first three numbers specify the red, green, and blue components
of the color. In this case the red would be zero, the green would be
one (255/255), the blue would be zero. This gives the standard
green color. You can change these values. I find that for daylight
black is visible in most conditions (the three values would be changed
to 0,0,0.
Also, during flight you can change between the day and night colors.
Look in the controls listing for something like "switch day and night hud"
and assign a keyboard combination to enable this command.
Be aware that any new updates will wipe out these changes and restore
the default green color. What I do is save a copy of my version and
substitute it for the updated version.
You can also vary the intensity of the hud with the "intensity" rocker
switch beneath the hud screen.