Mozilla's Firefox Web browser has a wide range of customizable options. Some of these options, such as setting your preferred home page, have easily accessible settings in the browser's interface. More complex options designed for advanced users lie within the "about:config" page. This method provides access to hundreds of hidden options for tweaking the browser, but making improper changes can cause the program to stop working.
Basic Firefox Settings
To open the Options window in Firefox, click the "Menu" button (or the "Firefox" button in versions prior to 29) and then click "Options." In the Options window, pick from the tabs such as "General," "Applications" or "Sync" to see all the available settings. After making any changes, click "OK" to save.
Advanced Firefox Settings
To change settings not present in the Options window, type "about:config" (without quotes) in the address bar and press "Enter." Click "I'll be careful, I promise!" to enter the configuration screen. A text list displays all options and their settings. To find a particular setting, type its name into the search bar. To change any setting, double-click it. Changing some of these settings can cause Firefox to behave erratically or stop working, so only modify settings you understand.