to change the default search engine (Google)

you must modify browser.search.defaultenginename

type in the address bar about:config

then press the button i'll be careful i promise

then type in the bar browser.search.defaultenginename

then right-click on it, select modify, type YAHOO (or other...), click OK,

exit firefox and restart-it.

or see also : Search Bar

Change the default search engine in address/location/awesome bar:

you must modify keyword.url in about:config

same as above and type in the bar for yahoo

http://search.yahoo.com/search?p=

or find other search engine in Keyword.URL

Change the default search engine in about:home it is a little more difficult see :

https://support.mozilla.org/en-US/questions/779082#answer-187996

except solution chosen read all the very useful replys.

thank you

Please mark "Solved" the answer that really solve the problem, to help others with a similar problem.

Firefox, Internet Explorer, Safari, Chrome, Opera = web browsers = display webpages

Google, Bing, Ask = search engines = find webpages

The first web page that you see when you open a web browser is the "homepage".

This worked like a charm! Thanks so much for the help. I hope that firefox will soon re-think its default search engine due to the privacy changes. I did not know of this until I read an article in the NYT and also online comments. It makes sense when I put in a question in the search bar of a site, I ended up seeing it when I logged into my google account and nearly lost my breakfast. Who would do such a thing? Well more than ever people need to re-think which search engine they want to use. I hope that google will re-think this, too, and offer options about privacy.

Why do all the "about:config" stuff when the Firefox help page tells us to click on the symbol in the left corner of the search box and pick another search engine. If the one you want isn't there, click "manage search engines" and you can add one.