hello, this sounds like a problem possibly caused by adware on your system. # to stay secure you should also update to a current version of firefox as soon as possible, since firefox 47 that you appear to be using currently has a couple of known vulnerabilities: [[Update Firefox to the latest version]] #afterwards go to the firefox ''menu ≡ > addons > extensions'' & remove any suspicious entries (toolbars, things that you have not installed intentionally, don't know what purpose they serve, etc). #run a full scan of your system with security tools like [https://www.malwarebytes.com/mac/ malwarebytes anti-malware] , which are specialised in adware and browser hijackers. [[Remove a toolbar that has taken over your Firefox search or home page]]