How to get App button back in S9|S9+?

From the Home screen, swipe up or down to access the Apps screen. Touch More Options > Home screen settings> Apps button. Touch Show Apps button, and then touch APPLY to get the Apps button back.

There’s a straight shortcut to access the app you were just using. It’s super convenient when you’re multitasking and need quick access to your apps. On the navigation bar, touch Recent to access all active apps.To open an app, touch it, and to close it, swipe to the left or right. You can also touch CLOSE ALL to close all running apps.