I applied a chart style to several charts in the same workbook, which each
link to the same three separate excel files. Each series is named for one of
these three files, and they are in the same order in all charts, however, the
order of the colors is different in each of the charts, and some even have
the color that the style would use for a fourth series even though there are
only three. I would like the data from each source file to be the same color
on all plots so it's not confusing to the viewer when switching between
charts in a presentation.

How does Excel decide which series gets which color if it's not determined
by series order? Is there a hierarchy (something like "series order") that is
hidden? How can I change this so that the "color order" is the same in all
plots? I could of course do this by manually each series, but would prefer to
understand what's going on.