We are having an issue where Mozilla seems to be setting the Paper/Output Paper Size to Letter and not A4 as configured on the printer drivers. There is quite a bit online regarding this, however everything we've tried has failed to resolve the issue. We have tried configuring the local prefs.js file - https://support.mozilla.org/en-US/questions/1239754 We have tried modifying the mozilla.cfg file We have also modified the following in about:config from within the browser itself...  Print.printer_printername.print_paper_name = A4  Print.printer_printername.print_paper_size_unit = 1 (This is the default value for A4) This is being used in a public facing environment. Because of this we are using group policies to clear down all sessions from within c:\users when the machines are rebooted. We had an issue recently to do with certificates, and injecting lockPref("security.enterprise_roots.enabled", true); into the mozilla.cfg done the trick. It is this file that is delivered to the endpoint devices using group policy. We are really hoping that there is something that we can modify to rectify this and would welcome any suggestions. Thanks