A friend has an online catalog in pdf format. When anyone opens it, it opens in the full-blown Acrobat, not the Reader. Additional toolbars at the top and Thumbnails and Bookmarks tabs cut down on viewable space. Why is the catalog opening the full Acrobat? Is there some kind of Open options setting to ensure it will open in the Reader?

The doc was saved in Acrobat 6 and then edited (adding some links and buttons) in 5.0.5.

Thanks in advance to anyone who can help.