The orientation information is saved as part of the layout file. If you need to work in both portrait and landscape mode, it would be best to save separate layouts based on the orientation. This way you could have a set for portrait mode and a different set for landscape mode.
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.