Norton browser will not stop making itself default ON IT'S OWN
https://community.norton.com/en/forums/norton-browser-will-not-stop-making-itself-default-its-own
I had a similar issue. Windows 11 Pro 23H2, Norton Private browser version 122.0.24315.112 (Official Build) (64-bit), Norton makes itself default automatically on running/starting the application
Also had an issue with updating NPB as it errored out claiming that it was unable to update due to inability to extract update files.
Norton Private Browser installed for testing...found Private Browser was default browser.
Norton Browser Core with Startup Apps = disable
Norton Private Browser with Startup Apps = disable
Norton Private Browser with Start menu = unPin
File type and protocol associations = change
=> machine Restart (not Shut down)