https://support.mozilla.org/en-US/kb/update-firefox-latest-version '''41.*''' New Tab Override (browser.newtab.url replacement) https://addons.mozilla.org/en-US/firefox/addon/new-tab-override/ With Firefox 41 (and higher), it's no longer possible to customize the page shown in a new tab via changing the preference browser.newtab.url in about.config. Because of the fact that hijackers abused the preference in the past, Mozilla decided to remove it (see bug 1118285). Fortunately, by removing it, Mozilla also introduced a new API to bring this functionality back to life as an add-on. This add-on allows the user to choose a certain page in a new tab. ----------------------- Your current version; Type '''about:config'''<enter> in the address bar. If a warning screen comes up, press the '''Be Careful''' button. At the top of the screen is a search bar. Type '''browser.newtab.url''' This tells Firefox what to show when a new tab is opened. If you want, right click and select '''Modify'''. You can change the setting to; '''about:home''' (Firefox default home page), '''about:newtab''' (shows the sites most visited), '''about:blank''' (a blank page), or you can enter any '''web page''' or '''about: page''' you want. The same instructions are used for the new window setting, listed as '''browser.startup.homepage'''.