Capture screen with physical buttons
The first method we recommend is to capture the screen with physical buttons on the phone. To do this take your Samsung Galaxy J7 Prime hold the power button and the home button at the same time
In a few seconds you will hear a little sound and see something on screen that will show that effectively capture was successful.
an image of what you're seeing on the screen at that time and you can access this screenshot via the phone gallery will be saved.
Capture screen via gestures
Another method that can be used in the Samsung Galaxy J7 Prime to capture phone is through gestures. There is an option in the settings in the "Movements and gestures" section that lets you enable a tip to capture screen with a gesture.
The gesture is to slide your hand on the screen from one side to the other, particularly from right to left. That catch again be saved to your gallery.
As you can see are two fairly simple alternatives to use, perhaps faster than the other but equally valid to capture everything that happens on your screen.