Win 10 64
When I click default browser, IE 11.xxx opens then is overlain with a dialog asking me to set bing as default search engine.

Since there is no way to close this dialog except through being forced to select bing, I have to open task manager to end it.

I searched registry for entry but found none. How do I change default browser?

I'm not at all sure whether the notes below will help, but they just might do so.

In The HTML Editor, 'Test With Default Browser' has a shortcut of Control+F9, and always selects IE 11, regardless of the default browser setting in Windows 10. The first Addional Browser has a shortcut of Control+F5. I use that shortcut and set the first additional one to Firefox, the browser set as my default for Windows 10. Setting the Addtional Browsers is via Tools > Preferences > Browser Testing tab.

As to the IE 11 search-engine matter itself, I would be inclined just to go along with the dialogue request. In the IE 11 cog-icon menu > Manage add-ons > Search Providers, one can right-click on the Bing entry and disable it, but I don't know whether that will stop the message from appearing. At the bottom left of that screen there is a link to 'Find more search providers ...' but it leads nowhere.

Frank

That is what I was afraid of. I find it kind of strange that the CC Editor does not have a reg entry where the default and list is stored. So simple unless MS paid them not to.