Search engine changed from Google to Yahoo

I am using both Safari and Mozilla Firefox with Google as my default search Google is set appropriately in all my browsers as the preferred search engine. This has just happened. Feel hijacked. Does anyone have suggestions as to how to fix this? I have tried to remove Yahoo Powered Search with uninstall and nothing happens. Looked for solutions and most are for Windows, where apparently this has been happening for a while. The posts for Mac solutions are from 2015 and the interface has changed since then so it's impossible to follow instructions. Not the end of the world but just super annoying! Not sure which community to use so am posting to Safari.