in firefox 24 you can change your search engine in Search bar - add, change and manage search engines on Firefox

its not search engine change homepage you like et a single website as your home page

If you like to keep things simple, here’s how to set your home page in three easy steps.

   Open the website you want to set as your home page. If you want a blank home page, open a new tab.
   Click the icon to the left of the web address, drag it to the Home button, and release.
   Home page Win1
   Click Yes to set this as your home page. 

Try it out: Click the Home button and your new home page will load in the current tab. It doesn’t get much easier than that! Set more than one website as your home page

This is the way to have one-click access to all of your favorite websites. For example, you can set the Firefox home button to open your email, favorite news site, and Facebook all at once.

   Open a new window and load the first web site you want in your home page.
   Click the new tab button and open the next web site. Repeat this step until you've opened all the desired sites in new tabs.
   At the top of the Firefox window, click on the Firefox button and then select Options
   Select the General panel.
   Click Use Current Pages.
   Home page Win2
   Click OK to close the Options window 

Try it out: Close all of your tabs and then click the Home button. Watch all of your chosen pages open up in tabs. Do it again! You know you want to. Note: Setting too many pages as your home page can make Firefox take long to start up. Restore the default home page

If you want to delete your home page customizations, this is the way to do it.

   At the top of the Firefox window, click on the Firefox button and then select Options
   Select the General panel.
   In the Startup box, click Restore to Default.
   Home page Win3
   Click OK to close the Options window 

Set what pages open when Firefox starts

This is a great feature you can use in addition to the home page settings. To save time, you can have Firefox open the pages you were visiting the last time you used it so you can continue where you left off.

   At the top of the Firefox window, click on the Firefox button and then select Options
   Select the General panel.
   In the Startup box, click the dropdown menu next to "When Firefox starts:" and select what Firefox should display when it starts up.
       Show my home page - Displays the home page(s).
       Show a blank page - Displays a blank page. This loads quickly since you don't have to wait for lots of tabs to load.
       Show my windows and tabs from last time - Opens the pages you were visiting the last time you used Firefox so you can continue where you left off. For more information, see Restore previous session - Configure when Firefox shows your most recent tabs and windows. 
   Click OK to close the Options window . 

Try it out: If you really want to get fancy, you can set a group of web sites as your home page and set Firefox to open the pages you were visiting the last time you used it. That way, you can pick up your work where you left off and have one-click access to your favorite sites. Tying it all together

Firefox is really flexible – "you" decide what works best. Keep it simple and set a single website as your home page or set up one-click access to your favorite web sites and save time by having Firefox pick up where you left off when it starts. What works best for you? Try and see! Having problems?

We have answers:

   If you keep getting the "Firefox has just updated" tab every time Firefox starts, see the article Firefox says it's just updated every time it starts - how to fix. 

   If your home page settings are not saved, see How to fix preferences that won't save. 

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You can use the SearchReset extension to reset some preferences to the default values.

• https://addons.mozilla.org/firefox/addon/searchreset/

Note that the SearchReset extension only runs once and then uninstalls automatically, so it won't show on the "Firefox > Add-ons" page (about:addons).

If you do not keep changes after a restart or otherwise have problems with preferences, see:

• http://kb.mozillazine.org/Preferences_not_saved