Launch Chrome, select the three dots in the top-right corner, and choose "Settings." In "Settings," on the left sidebar, click "Search Engine." Then, on the right pane, choose "Manage Search Engines and Site Search." Scroll down to the "Search Engines" section. Here, next to a non-Bing search engine, click the three dots and choose "Make Default."

To change the default search engine: Launch Chrome. Click the three-dot menu on the top right. Click Settings. Select Search Engine. Select the engine of your choice from the list of search engines in the drop-down menu. If the browser search engine keeps resetting back to Bing despite that, you'll need to remove the adware or malware responsible.