press '''CTRL + 0''' (zero) to '''Reset Zoom''' How do I use Zoom? * https://support.mozilla.com/en-US/kb/how-do-i-use-zoom The Firefox Page Zoom feature does a domain by domain level of saving the users preferred zoom level settings, there is no default Page Zoom level setting in Firefox. Try these extensions: -> Default FullZoom Level 4.5 * https://addons.mozilla.org/en-US/firefox/addon/6965 -> NoSquint 2.1.2 * https://addons.mozilla.org/en-US/firefox/addon/2592/ Check and tell if its working.