Go here.
Eagle Dynamics/DCS World Open Beta/Mods/aircraft/A-10C_2/cockpit/scripts/HUD/Indicator/HUD_init
Now, cut and paste the HUD_init file to your desktop. Double click the HUD_init file and scroll all the way to the bottom. You'll see a line day color {0, 255/255, 0, 255/255}
Change it to {0, 0, 0, 255/255}
Save it and cut/paste the HUD_init file back into the Indicator folder.
One more thing when you're doing this. When it asks you if you want to continue. Click the continue button.
When it the cockpit. You're need to brighten up the black font with the iten rocker switch.