After you've saved the file on the Desktop and double-click, does it still try to open with LiveType or with Preview? If you have to right/control-click to open it with something other than LiveType I would suggest that you bring up the Get Info window, under the Open With section select Preview, and click Change All to change the file associations. If you want to go the shotgun approach you can pull the com.apple.LaunchServices.plist in ~/Library/Preferences but other filetypes will be affected. You can also look in LiveType's preferences to see if you can change the file associations it has...