Hi, is there something wrong ? Has it just appeared ? You can click on the Search Box and Click on Change Settings from the Drop down. Which will take you to Options--> Search where you can find Yahoo in the list of Search Engines. Click on Yahoo and remove it. If yahoo switched your previous Search Engine then you possibly have some malware. Did you install anything like AdAware or Web Companion from Lavasoft ? Please scan with https://www.malwarebytes.com/mac if this issue just appeared.