OP here...

I had a different browser set as default. Opera was a back-up system. Opera was never set as the default browser.

This behavior seems to have started with the last 1-2 updates.

After updating Opera I have to go into the Win10 CP and reset the default browser there as well as a few additional file types as Opera also hijacks the default PDF reader which I had set to Adobe reader itself.

If you need to uninstall the resident version to avoid this, that is a problem.

The "Accept and Update" suggests that it will respect system settings and preferences. It is not from my experience. At the least it should ask me if I want to make it the default browser. It is not asking.