hello, could you go to the firefox menu ≡ > help ? > troubleshooting information, copy the contents of that page and paste them here into a reply on the forum? this might give us a clue what is going on...

deleted some too many characters & can't upload txt file. Then ran into your spam prevention print.printer_Microsoft_Print_to_PDF.print_headercenter: print.printer_Microsoft_Print_to_PDF.print_headerleft: &T print.printer_Microsoft_Print_to_PDF.print_headerright: &U print.printer_Microsoft_Print_to_PDF.print_in_color: true print.printer_Microsoft_Print_to_PDF.print_margin_bottom: 0.5 print.printer_Microsoft_Print_to_PDF.print_margin_left: 0.5 print.printer_Microsoft_Print_to_PDF.print_margin_right: 0.5 print.printer_Microsoft_Print_to_PDF.print_margin_top: 0.5 print.printer_Microsoft_Print_to_PDF.print_oddpages: true print.printer_Microsoft_Print_to_PDF.print_orientation: 0 print.printer_Microsoft_Print_to_PDF.print_page_delay: 50 print.printer_Microsoft_Print_to_PDF.print_paper_data: 1 print.printer_Microsoft_Print_to_PDF.print_paper_height: -1.00 print.printer_Microsoft_Print_to_PDF.print_paper_name: print.printer_Microsoft_Print_to_PDF.print_paper_size_unit: 0 print.printer_Microsoft_Print_to_PDF.print_paper_width: -1.00 print.printer_Microsoft_Print_to_PDF.print_resolution: 600 print.printer_Microsoft_Print_to_PDF.print_reversed: false print.printer_Microsoft_Print_to_PDF.print_scaling: 1.00 print.printer_Microsoft_Print_to_PDF.print_shrink_to_fit: false print.printer_Microsoft_Print_to_PDF.print_to_file: false print.printer_Microsoft_Print_to_PDF.print_unwriteable_margin_bottom: 0 print.printer_Microsoft_Print_to_PDF.print_unwriteable_margin_left: 0 print.printer_Microsoft_Print_to_PDF.print_unwriteable_margin_right: 0 print.printer_Microsoft_Print_to_PDF.print_unwriteable_margin_top: 0 privacy.clearOnShutdown.cookies: false privacy.clearOnShutdown.sessions: false privacy.cpd.sessions: false privacy.sanitize.migrateClearSavedPwdsOnExit: true privacy.sanitize.migrateFx3Prefs: true privacy.sanitize.sanitizeOnShutdown: true privacy.sanitize.timeSpan: 4 privacy.trackingprotection.pbmode.enabled: false security.default_personal_cert: Select Automatically security.sandbox.content.tempDirSuffix: {b8f7ed23-a932-46b8-89f0-47410a18b3d1} services.sync.declinedEngines: services.sync.engine.passwords: false storage.vacuum.last.index: 1 storage.vacuum.last.places.sqlite: 1480105580 ui.osk.debug.keyboardDisplayReason: IKPOS: Touch screen not found. JavaScript Incremental GC: true Activated: false Prevent Accessibility: 0 NSPR Expected minimum version: 4.12 Version in use: 4.12 NSS Expected minimum version: 3.26.2 Version in use: 3.26.2 NSSSMIME Expected minimum version: 3.26.2 Version in use: 3.26.2 NSSSSL Expected minimum version: 3.26.2 Version in use: 3.26.2 NSSUTIL Expected minimum version: 3.26.2 Version in use: 3.26.2 Content Process Sandbox Level: 1

thank you, could you try if the manual steps in the following article work for you: Pages appear tiny when I print or view them in Print Preview (please disregard the title & the claim that the issue is already fixed in your case)