To take a screenshot on a Samsung Galaxy S8, press and hold the Power button and Volume Down button at the same time. You can also enable Palm Swipe in Settings, then swipe the edge of your hand across the screen to capture it.
To take a screenshot on a Samsung Galaxy S8, press and hold the Power button and Volume Down button simultaneously for about 1–2 seconds. The screen will flash, and you’ll hear a shutter sound. Screenshots are saved in the Gallery under the “Screenshots” folder.