Ok. I'm confused. I did not have any notifications on the Always On Display; that is until I made sure it was turned ON. However, I could not turn it ON since my phone was in power saving mode. Once I turned off power saving features, the Always On Display now shows notification Icons for mail, messages, etc. a clock, weather info and of course the fingerprint thing as well as on the very bottom that oval screen that now says Have a good day and a faint showing in the background of the wallpaper I installed.
If I press the on/off key when on the Always On Display screen it goes to what I refer to as the lock screen since it shows a small lock icon on the top and even if it shows full notifications it takes a fingerprint to open to go to the UNLOCKED screen, so I can then review the messages, texts, etc. (And honestly, even if I have been playing with the phone all day, I cannot remember if there were any notifications on the LOCK SCREEN or not until I got the Always On Display screen working.
Sorry if this is not what the subject matter is about. I do know how to navigate around the phone to get it setup like the S24U being returned; however not just that fluent in all the terms such as LOCK SCREEN vs. Always On display, etc.
Hopefully, this helps others and if I am way out in left field...sorry to add confusion.