You can try to update by going to Tools (Alt + T) > Add-ons and click the gear icon on the top right and Check for Updates. This will try to update all the add-ons in one go. To update individually, click Extensions on the left and right-click an add-on and Find Updates.
What's That Preference? add-on - Quickly decode about:config entries - After installation, go inside about:config, right-click any preference, enable (tick) MozillaZine Results to Panel and again right-click a pref and choose MozillaZine Reference to begin with.