How to change the highlight color and not just the flag color

I have found information on how to change the color of flags in Outlook, but
I have not found anything that allows for the change of the actual color that
is shown when you click on the flag created. It seems that even though I
might create a White flag, the color shown whne I click on it is the color of
the flag that I copied to create the white flag.

Is what I looking for even possible? if not why even give the option to
create a flag when you are stuck with the default colors?

Thanks