The runtime assigns the initial foreground and background colors as specified by your program. If you use the REVERSE option, the foreground and background colors are exchanged for each other. If the output device is monochrome, then the colors are transformed to black or white at this point.
There are no configuration options that affect this step, except for the MONOCHROME option, which forces the colors to be set to black or white, as if the output device is monochrome. To enable this option, set it to a non-zero value.