Hello,

did you try changing your default search engine in settings? If not, please do the following:

1. Click the menu button and select Settings.
2. Select Search in the left pane.
3. Use the drop-down menu under Default Search Engine to choose the search engine you wish to use by default.

See Change your default search settings in Firefox for more details.

Hi Elena, sometimes an add-on hijacks your searches because they have a paid relationship with Yahoo. So if the first solution didn't work, please take a look here:

You can view, disable, and often remove unwanted or unknown extensions on the Add-ons page. Either:

• click the Extensions button (puzzle piece) on the toolbar > Manage Extensions
• Ctrl+Shift+a (Mac: Command+Shift+a)
• "3-bar" menu button (or Tools menu) > Add-ons
• type or paste about:addons in the address bar and press Enter/Return

In the left column of the Add-ons page, click Extensions. On the right side, find the "Manage Your Extensions" heading.

If there is at least one extension before the next heading -- "Recommended Extensions" -- please continue:

Then cast a critical eye over the list below that heading. Any extensions Firefox installs for built-in features are hidden from this page, so everything listed here is your choice (and your responsibility) to manage. Anything suspicious or that you just do not remember installing or why? If in doubt, disable (or remove). For your privacy and security, don't let mystery programs linger here.

Any improvement?

Note: Sometimes extensions can frustrate access to this page. In that case, first restart Firefox in its Troubleshot Mode and then try again. See: Diagnose Firefox issues using Troubleshoot Mode -- Open, not Refresh.