Important: If a website doesn’t have an encryption icon, the words “Not Secure” appear in the Smart Search field. Don’t enter personal or financial information on a webpage that isn’t encrypted. The website you’re visiting might not be the website you want, and information you enter is vulnerable to theft. Instead, go back to the page where you logged in and check for a link to another version of the site that’s encrypted—for example, “Use our secure site.” If available, use it, even if you don’t expect to view or provide private information.
In the Safari app Change Search preferences in Safari on Mac