When data points overlap (or are superimposed) on an XY graph, the plotting order determines which will show on top.
The two graphs in this example are identical except that the plotting order was reversed. Note the green symbols are behind the clear ones in the graph on the left, and in front on the graph on the right.
To change the front-to-back order of the data sets on a graph:
Click the Rotate/Flip button in the Change section of the Prism toolbar to reverse the front-to-back order of data sets on a graph.
To fine tune the front-to-back order, go to the Data Sets on Graph tab of the Format Graph dialog.
Changing the order of the data sets on this dialog changes the font-to-back order of the data sets on the graph. It does not change the order of the legends.
Front to back order within a data set
Within a data set, the front-to-back order of plotting is determined by the order of rows in the data table. The first row is furthest back and the data entered in the last (bottom) row is plotting in front. If you need to control which point is on top, change the order of the rows.