Hi, @Mbfrenchbulldogs. Congratulations on securing the brilliant new S23 Ultra! I'm sure you'll be absolutely delighted with your new phone when it arrives. 😍
Our colleagues from Samsung Canada have created a handy guide about using the Auto switching feature:
This would typically be contingent on your earphones being Buds, so the headphones you were using when watching Unpacked may not have been compatible with Auto switching.
Are you still receiving the error message about DeX?