Help with duplex printing

NT Workstation 4.0 users printing to an HP8100 select “print on both sides”(in MS Word) and it will print on both sides, but the next day after re-starting their PC they have to reselect the “print on both sides” again. How do I get this setting to be saved on the user’s PC? I’m not sure if this is a Print server issue or a desktop issue…any help would be appreciated.