My download of flash changed my search engine to Bing

It sounds like you downloaded a bogus version of Flash. This happens if you attempt to update Flash Player because a pop-up told you to. Only download Flash Player updates from either The Official Adobe Website or from System Preferences > Flash Player > Check for Updates. Other downloads of Flash will contain malware.

Download and run Malwarebytes. Malwarebytes was developed by one of our own colleagues here in ASC and is about the most proven anti-malware software for Mac.

After that restart and go to Safari menu > Preferences > Search and choose the search engine you want to use.

Jay, I didn't see the screen name or I would've known!