Type '''about:addons'''<enter> in the address bar to open your Add-ons Manager. Hot key; '''<Control>''(Mac:<Command>)''<Shift> A)''' In the Add-ons Manager, on the left, select '''Extensions.''' Remove yahoo '''Anything.''' Now do the same in the computers Programs Folder. '''Windows:''' Start > Control Panel > Uninstall Programs. '''Mac:''' Open the "Applications" folder. '''Linux:''' Check your user manual. ------------- You may have ad / mal-ware. Further information can be found in the [[Troubleshoot Firefox issues caused by malware]] article. Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.