HOW DO I CHANGE MARGINS FROM MILLIMETERS TO INCHES FIREFOX
To manually switch your printers from mm to in:
(1) In a new tab, type or
paste about:config in
the address bar and press Enter/Return.
(2) Click the button
promising to be careful.
(3) In the search box above
the list, type or paste size_u and
pause while the list is filtered
(4) For each printer that
has its print_paper_size_unit set
to 1 (millimeters),
double-click it and edit the value to 0 (inches) and click OK.
(5) Click OK.