When you choose "Export as Text…" from the “File” menu, you are presented with a standard file dialog asking you to name the file you want to save the text in. At the bottom of the dialog are two radio buttons, “CERN” and “NCSA”. The default is whatever you set in your preferences for the document you are working with. You can change the output format at this time by clicking on the radio button that represents the type of format you want.
