I looked up online on how to set a Powerpoint (for Mac) presentation (2007) to open as a slideshow automatically upon opening. They all said to change or save-as file extension from 'pptx' to 'ppsx', and this will auto open as a slideshow. However, after doing this and reopening it actually opens in Keynote. Even the file is under the 'Keynote' heading in Finder. What is going on? How do I set Powerpoint to open automatically on slideshow when i email to others? Thanks.