Google search hijacked to yahoo
I hope someone can help with this. Yesterday I noticed any search in Google directed to Yahoo. I've tried all the suggestions online. There are no extensions in my preferences, I've cleaned out my cache, deleted all my history, I ran Malwarebytes, which found 3 PUP files and deleted them. This didn't sort the problem. I've manually searched for rogue apps or files in the library following some guidance on another page, but found nothing.
In developer mode in Safari I disabled javascript - I'm not a specialist, by this time was trying anything! - and it stopped the highjack to Yahoo and came up with an address in the browser (see below). I've searched for anything related to searchitnow but can't find it. I tried upgrading to Mojave hoping that it would solve it, but it didn't work either. There is some script being enabled when I do a Google search, I've downloaded Firefox and it isn't affected. Does anyone know if I can search for this Javascript command in terminal or something? I've spent hours on this and I'm getting nowhere.
iMac, macOS Mojave (10.14)