First, XL is not a stable platform for controlled forms unless your
users respect the protection you apply (it's a trivial exercise for
anyone who's able to find these groups, to remove cell protection). So
the first way is to tell your staff to leave the headers and footers
alone. And make sure they're generating the forms from a read-only
template rather than working on the original (of course, they're
probably just copying their last saved workbook).
Short of removing the Header and Footer and Page Setup options from
their menus, one way I've implemented before is to include
Workbook_BeforePrint() and Workbook_BeforeSave event macros that set the
headers (usually after validating the form).