I just installed Windows 10 1803.

I like Cortana for finding things on my computer.
But I never want Cortana to run a Bing web search.

I don't want to use Cortana for finding things on the net.

For that, I can use my own browser set to my choice of search engine.

How do I turn off Cortana's connection to Bing on the net?
At the same time keeping Cortana's searches on my computer?