For those using Poser 4 who don't have acess to Python I have written a pz2 (pose) file to reset the display mode of standard human figures to USEPARENT (the default setting). Open the link above, copy the text into a text editor, then save it to a Pose folder as "USEPARENT.PZ2". In Poser apply the pose to each figure in the document.

For props and nonstandard figures I'm afraid you will just have to reset them manually.