Recently all of my apps have been opening in full screen despite holding the S8+ vertical. I have tried to fix via settings>display>full screen but many of the toggle buttons are greyed out in the on setting. No matter how I rotate my device it stays locked in full screen oriented with volume buttons down
It seems your phone might have had the option to auto rotate the screen turned off. If you pull down the quick settings menu from the top of the phone, t here should be an option to turn auto rotate on and off. Can you make sure it is turned on?