If you place several graphs on a layout, you can create a master legend that applies to all the graphs as shown below.
It took four graphs to make this figure. The first three graphs show data, and the fourth (not shown) was used only to create the master legend. Follow these steps:
1.Duplicate one of the graphs to create another graph that won't be shown in the layout, but will be used to create a legend. To create a legend on this graph, double-click on a symbol to bring up the Format Graph dialog. Click the Global button to change all data sets. Then check Show Legend.
2.Create a layout and assign the graphs (three in this example).
3.Select and copy the legends from the extra graph and paste onto the layout (Paste Drawing). That is a simple copy and paste operation and does not use a placeholder.
Notes about master legends:
•The master legend is linked to the graph from which it was copied. If you change the symbols in that graph, Prism will update the master legend.
•Master legends on a layout have exactly the same size as the legend on the graph from which you copied the legends. When you place graphs on layouts, you can shrink or expand it to fill a placeholder. You can't do this with master legends. The only way to change the size of the symbol and lettering in the master legend is to change the font size and symbol size on the graph used to create the master legend. This is done in the graphs section, not the page layout section.
•After copying a legend, you can only paste it into a layout. It is not possible to paste a legend onto another graph.