How to customize colors in High Contrast: Once you have selected High Contrast color scheme, you can switch to normal and back using Alt+ Shift+ PrintScreen. On the other hand, visual user experience is limited.
Unlike in normal color schemes, colors in High Contrast are completely customizable and Windows obeys them. If you need custom window color due to health issues so you are OK with some spartan appearence, then switch your color scheme to High Contrast and customize the colors there. (Active Title, Inactive Title, Window Text, Window, Control Text, Control.
Since Windows 8.0, colors are NOT changeable like they used to be.