This happened to me the other day. I went to File Printer Setup and the Landscape option was greyed out.
found the default printer to be the "Microsoft XPS Document Writer".
Once I changed it to an actual, physical printer, the Landscape option
was available again.
Now, the real moral to the story here is that the Crystal Designer will make itself as large as the paper specified in whatever printer is defined. So, should you ever need more "real estate" on your report, you can always increase it by specifying a larger paper size.