How Can I Change the Number of Colors?

The standard generic display in Windows 3.1 used only 16 colors. Most
multimedia programs, however, require 256 colors, and a lot of painting
programs require all possible colors. First of all, forget about your monitor;
all monitors are capable of displaying an infinite number of colors. What
matters is how many colors your video card is capable of sending to the
monitor. So the first question you have to answer is: what brand and model
of video card does you computer have?
If you're lucky enough to have Windows for Workgroups and you only need
256 colors, then you can change the display settings to Super VGA 640x480,
256 colors no matter what kind of video card you have. This is a generic
driver that works with all SVGA-compatible video cards.
In all other cases, you will need to consult your
video card's documentation to find out which is the correct driver
to use, and how to change the settings.
Note that if you run at higher resolutions, you reduce the maximum amount
of colors that your video card can produce. This is because more colors
requires more memory, and so does higher resolution. The following table
can be used as a general guideline to tell how much video memory you will
need for certain resolution/color combinations, but keep in mind that your
particular video card may be different because of memory timing requirements.