By default Firefox use Google.com in search engine bar , but you can change it your country domain or language ,and more easy your web surfing .
Follow these steps -
1. Click this link google search plugins and choose your plugins.
2. Click on link-1 and then click add
3. Now click on search engine bar and select Manage search engines…
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Many, many thanks. I have just wasted 2 hiours of my life trying to get back to the UK version of Google I used until the computer/browser/Google decided to change it. Yours was the only easy sensible way that worked.