Not only has Mozilla replaced Google with Yahoo! as Firefox's default search engine, it also revamped the way its search bar functions. Formerly a typical search box, which also contained a drop-down menu that allowed you to change the default engine on-the-fly, the new UI offers several new features -- highlighted by One-click Search.
This tutorial applies to Mozilla Firefox 78.0 on Linux, Mac, or Windows.
Use One-click Search in Firefox
With One-click Search, Firefox allows you to submit your keyword(s) to one of a number of engines from within the Search Bar itself. It recommends 10 search keyword sets based on what you have typed in the search bar. These recommendations originate from two sources: your past search history and suggestions provided by the default search engine.
Open your Firefox browser and begin typing in the search bar. In this example, we entered the word "yankees."
You can choose from several popular providers such as Bing and DuckDuckGo, as well as to search other well-known sites like Amazon and eBay. Enter your search terms and select the desired icon at the bottom of the search recommendations.
To modify search settings, select the Change Search Settings gear icon to the right of the search engine icons.
The Search Options page opens. The top section, labeled Default Search Engine, contains two options. The first, a drop-down menu, allows you to change the browser's default search engine. To set a new default, select the menu and choose from the available providers.
Directly below this menu is an option labeled Search Suggestions, where you can choose how suggestions from search engines appear by selecting or clearing check boxes.
The One-Click Search Engines section lists the search engines available, accompanied by checkboxes. When checked, that search engine will be available via One-click. When unchecked, it will be disabled.
To add more search engines, select Find More Search Engines below the One-Click Search Engines list.
Select the search engine add-on you want to install and choose Add to Firefox.