If I've understood correctly you want to change the colour of layers in either a layout or schematic for better viewability.
This is done through the file display.drf which usually resides in the working directory, or possibly in the library directory.
This file can be modified using a text editor, or using the Display Resource Editor tool (Tools -> Display Resource Manager
from the menus) .
If you are colour blind then you may wish to look at this article.
Hopefully this will help to answer your question?