Setting A4 no matter what the printer

[grant]

I am sure this has been raised before but I can't find it in FM Forums.

I have helped set up a number of reports at schools, and in some cases they switch between laser printers and deskjets. They are always set to A4, but they set up differently on the page and sometimes print off the page etc. How do I set pages, so that no matter what printer they face, A4 prints properly on the page.

Any help gratefully accepted.