Extension developers frequently offer updates to their extensions. Firefox offers a number of ways to update your extensions. If you are like me and need constant reminders, your best bet is to configure Firefox to check for updated extensions automatically. This preference is on by default, so if you decide you don't want Firefox to check for updates automatically, you must go into the Advanced Preferences and uncheck the box under Software Update that is labeled My Extensions and Themes.
If updates are available, Firefox alerts you by displaying a color-coded icon in the upper-right corner of the browser window. Here is the breakdown of what the color codes mean:
If you decide you want to check for extension updates manually, you can click the Update button in Extension Manager. The update wizard launches and guides you through the process.