You can switch the search engine from the search bar that is automatically in Firefox by clicking the downward pointing arrow and switching it to your choice.

If you want a custom search engine, you can navigate to that website, click the arrow and click "Add <custom engine>. Example below:

If you don't want the search bar, you can "hide" it from view by clicking the 3-bar menu button, going to "Customize" at the bottom, then dragging the search bar back into the Additional Tools & Features box.

Once you change the search engine in the search bar, you can hide the search bar and search using the address bar with the provider you chose in the Search Bar.

Sorry for that, it may well have changed the default search engine, depending partly on where you are or what version of Firefox it is.

This should be easily changed back to one of the other built in search engines including Google. If you can not do that something is going wrong. Maybe you are just closing the tabs. You need to set the default search engine, as explained lower down in this post.

• See this general article. Noting that setting the search bar search option sets all other searches. Search bar - add, change and manage search engines on Firefox

I will also copy the standard reply, which includes instructions  :

Thank you for your question about the search changes in Firefox. There's been a lot of exciting news and we are happy to assist you.

What has changed?
In the US and Canada, the default search engine has been changed from Google to Yahoo. In Russia, Yandex Search will become the default search and in China, Baidu will continue to be the default search. However, all other search engines will still be available in these regions. You will notice this change in Firefox 34.

Would you like to know more about the change?
See the blog post written by Chris Beard, New Search Strategy for Firefox: Promoting Choice & Innovation and the News Release, Yahoo and Mozilla Form Strategic Partnership.

Do you want to change your default search engine?
In Firefox 33 or below, you would change your default search engine from the Search bar, as shown in this animation. Starting in Firefox 34, you can use one of these methods:
Note: The following may not apply to localized versions of Firefox.

• Click the menu button and choose Options on Windows or Preferences on Mac or Linux, then select the Search settings panel.
• Click on the magnifying glass icon in the Search bar, then click on Change Search Settings, as shown here:

In the Search settings panel that opens, select a different search engine from the drop-down menu (see this screenshot).

For more information, see the article Search bar - add, change and manage search engines on Firefox.

Let us know if this answers your questions. If you have any other questions, we are happy to help.

<rant> Personal Opinion It really annoys me that Firefox makes changes that are likely to be unpopular or a problem to at least some users but does not explain in advance what changes are being made and what to do if you do not like them. This is something Firefox support staff may be discussing* with contributors next week. Maybe we will be able to make policy changes to prevent or mitigate this reoccurring type of problem </rant>

Sourjobraato Banerjee

From what you are saying it sounds rather as if you understand what is happening and have already made the necessary changes.

You are asking to do more than just revert to Google. If you have not actually already solved your problems it is probably better if you start your own question. If you do so please post back in this current thread to confirm that, so the threads are cross linked.

Bookmark and use this; Download the Mozilla Search Reset {web link} This add-on is very simple: on installation, it backs up and then resets your search preferences and home page to their default values, and then uninstalls itself. This affects the search bar, URL bar searches, and the home page.

John99 said

Sourjobraato Banerjee From what you are saying it sounds rather as if you understand what is happening and have already made the necessary changes.

His post was just a copy+past of a post and reply from another thread. I removed the post part so it would make more sense. He tends to copy+paste whole parts of a sumo article instead of linking to it for example.