what's your process for making google preferred search engine?

it's a browser setting, not a google one, so it depends what you use. chrome: settings > search engine. edge hides it under privacy, search and services, right at the bottom in address bar and search. firefox: settings > search. on an iphone it's in the phone's settings app under safari rather than inside safari itself. if it switches back on its own, look at your extensions before anything else.