Gesture navigation on the Samsung Galaxy A7 (2018) could be part of Sammy's Android Pie update
If you choose to go with the gesture navigation, you might want to make sure that the gesture hints are toggled on. These hints show you where on the screen you need to swipe for a certain action to occur. For example, if you swipe up following the "hint" on the left of the screen, you will see the recent apps screen. Swipe up from the middle "hint" to go home, and from the right "hint" to go back. If you don't want to see the hints, simply toggle the switch to off. But be forewarned. If you do turn the "hints" off, you might end up using the swipe gesture on the wrong part of the display and return to the home screen when you meant to go to recent apps.

The Samsung Galaxy A7 can replace navigation keys with gesture navigation
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