Enabling Show only modified preferences in about:config the page shows even those that the user changed in the settings page so I suggest adding a drop-down menu to choose between Show all, Show only modified preferences and Show only preferences modified on this page. This way users that change an option on about:config and don't remember which one they changed will find them easier. Additionally (but not necessary), you can set a way to save the choice to use it as default for the next time about:config is opened again.