Choose Plot > Variable Settings. The Show Markers pop-up menu controls the number of markers that are displayed. For Scatter plots, your only option is to show All of the markers. Line plots give you the ability to control the number of markers and the type of line, if any, to be displayed on the plot.
KaleidaGraph is a thoughtfully designed graphing and data analysis application for research scientists, as well as for those in business and engineering fields. It produces publication-quality graphs, and easily converts the most complex data into a functional display.