still can't change search provider - what am i missing?

which browser? in chrome it's settings > search engine > manage search engines and site search, and the catch is the engine has to be in that list before you can make it the default. if the option is greyed out, something is managing it, a work policy or an extension. type chrome://policy in the address bar to check, and try disabling extensions one by one. edge is similar, settings > privacy, search and services > address bar and search, right at the bottom of that page.