Firefox keeps changing your search engine? Check the default and extensions

Type a phrase such as weather tomorrow into the address bar. Submit it as a regular search without picking an alternate engine or a keyword shortcut. Check the provider on the results page. Firefox can also send a single search to a different provider, so compare that result with the default shown under Settings → Search.

Mozilla sometimes changes the providers available in a region and may show a notification about a new default. If your usual provider is still listed, select it again and restart Firefox to check whether it sticks. If it is absent, check which engines are available in Search settings before installing an add-on.

In the Firefox menu, open Help (or Help and Report) → Troubleshoot Mode, then choose Restart and Open. Check the default and try the same search. If the problem goes away, reopen Firefox normally, then disable recently added search or toolbar extensions one at a time and retest. Keep the extension disabled or remove it once you identify the cause.

If the problem also occurs in Troubleshoot Mode, record the default listed in Search settings and the actual results provider. Note whether the selected engine changes after restart or stays the same while results open elsewhere. Those details make it easier for Mozilla Support to identify which setting or behavior to investigate.