When I add curves to my Prism graph, why don't they match the color of the associated data points?

From a Prism graph's 'point of view', a curve is just another data set. Graphs don't really know which curves belong to which data sets. When you apply a color scheme to a graph that contains both data points and curves, Prism just goes down the list of data sets applying colors. Each curve is just another data set, so the color of the curves doesn't match the symbols for the associated data points.

The workaround in Prism 4 is to apply color to the symbols on your graph before doing your analysis and creating your curve. Then, any newly created curves will match the color of the symbols. One easy way to do this is to set a color scheme as a default in the Edit/Preferences menu. That way, all graphs will automatically have a color scheme applied and the color of curves and symbols should match.