I'm assuming this is the XTREE-embedded print feature, which bases the print view on the screen view. The screen view shouldn't be affected by the physical dimensions of the monitor, but will be affected by the resolution and the desktop/font adjustment factors, and possibly by the size of the original main window. Partly that depends on whether the tree is within a dialog using MBF_ALTPOS or not. In the MBF_ALTPOS case, the XTREE size units are based on the standard desktop font size. Otherwise they're based on the main window grid size. And then to further complicate matters, the tree may be allowing the user to save a custom configuration, after which all bets are off in terms of why one workstation has a different layout than another.
If you added the $RESETCFG option to your PopupMenu, you might start by having the two users use it to reset their configurations to the default. But ultimately if you want the print option to look a certain way, you have to first get the XTREE view to look that way, whether by manually resizing the columns and or the tree itself, or by adjusting the font scale.