Changing your search engine is going nowhere

If the extensions are clean and it still flips, check for a program installed alongside some free software - on Windows look in Apps for anything you don't remember installing. On a Mac the usual culprit is a configuration profile, under System Settings. Then reset Chrome settings once you've removed it, otherwise it just comes back.

If it keeps switching back on you, that's almost always an extension or a program that installed a search hijacker. Go through your browser extensions first and remove anything you don't recognise, then set the default again in settings under Search engine. In Chrome also check the 'On startup' section, and if it still won't stick, reset settings. On a work laptop it can be a policy set by IT - the browser will usually say it's managed by your organization if so, and then you can't change it yourself.