How can I change the default page orientation for new graphs and layouts?

Each graph or layout in Prism can be a portrait or landscape page. To flip a page, use the rotate button on the Change part of the tool bar, or drop the Change menu and choose Flip...

When you make a new layout, you choose if  you want it to be landscape or portrait. This choice then becomes the default for the next layout you make. With Prism 5.00, 5.01 and 5.0a this choice also becomes the default for new graphs. So if Prism makes new graphs in portrait and you want them to be landscape, go make a new layout in landscape orientation. From then on, Prism will make new graphs in landscape.

Prism 5.02 (Windows) and 5.0b (Mac)  have a new setting on the New Graph tab of the Preferences dialog to specify the default orientation of new graphs. 

You will also find a spot to choose landscape vs. portrait on the Printer Setup (Windows) and Page Setup (Mac) dialog. Prism ignores these settings for graphs and layouts. The problem is that those dialogs are designed to make one choice per document, while Prism allows a mixture of landscape and portrait sheets within one project document.