If any search engines you have installed has an update (like a new icon, new location, etc.) then it will be updated automatically.

Are you talking about the search engines that are installed by default or only search engines that the user has added? Are the search engines you're talking about to the right of the Address bar? Google, Yahoo, Bing, Amazon.com, eBay, Twitter, and Wikipedia (en)?

What do you mean by new location?

How do I update these manually?

All the search engines, those installed manually and those that are installed automatically by Firefox. By new location I mean if the search engine decides to change the exact URL they want users to go to.

Are there any Articles or links about this option?

Is there a way to update manually?