Does this help https://support.mozilla.com/en-US/forum/1/688704

Chris, no that does not help because my keyword.url is already set to google.

Maybe a problem with an extension ( Search Settings Plugin ?)

Start Firefox in Use Troubleshoot Mode in Firefox to check if one of your add-ons is causing your problem (switch to the DEFAULT theme: Tools > Add-ons > Themes). See Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems and Troubleshoot issues with plugins like Flash or Java to fix common Firefox problems

If it does work in Safe-mode then disable all your extensions and then try to find which is causing it by enabling one at a time until the problem reappears. You can use "Disable all add-ons" on the Safe mode start window to disable all extensions. You have to close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

cor-el, yes 'disable all add-ons' worked. Thanks much.