Samsung video shows you how to customize the Galaxy S9/S9+ screen

The first step, as many Android users know, is to long press on the home screen. This reveals a number of theme options. After tapping on the one that catches your fancy (and be careful, when your fancy is caught it can hurt like hell), make sure you tap on "Apply." 

You can also customize the clock on your home screen. Go to Settings > Lock Screen and security > Clock and FaceWidgets. Click on the Clock style that you like the best. You can also add lists to your Always-On Display by tapping on Reminders to create a list which can be pinned to the display. Once the phone locks, your list shows up on the screen. You'll have no more excuses for forgetting the milk when you go shopping on your way home from the office.

Don't forget to check out the video at the top of this article. Oh, one last thing; don't try this on an Apple iPhone.

source: Samsung