Similar to Galaxy S8, Galaxy S9 features software navigation buttons. And Samsung allows you to hide and customize Galaxy S9 navigation bar and navigation buttons in Galaxy S9 and S9+.
You can also use the software home button even when the screen is off.
This Galaxy S9 guide shows you how to hide and unhide Galaxy S9 navigation bar, customize the background color of Galaxy S9 navigation bar, customize the Galaxy S9 navigation button layout, and how to use Galaxy S9 Home button when the screen is off.
How to lock Galaxy S9 navigation bar?
By default, when you get the new Galaxy S9 or S9+, the navigation bar is shown, but not locked.
The dot (official name: show and hide button) on the left side of Galaxy S9 navigation bar indicates you can hide the status bar if you want.
Sometimes, you may not want to use the feature of hiding and unhiding the navigation bar, i.e., you may want to lock Galaxy S9 navigation bar.
To lock Galaxy S9 navigation bar, you may go to Galaxy S9 Setting, tap Display as shown below.
Then in Display settings page, tap Navigation bar as shown above.
In Navigation bar settings page, tap Show and hide button (marked as 1 in the screenshot below).
After you hide the button, then you lock the navigation bar in Galaxy S9 and S9+.
If you want to hide Galaxy S9 navigation bar, then you need to enable (show) this button.
Showing the show and hide button does not mean the navigation bar will be hidden automatically. You need use this button to hide and unhide Galaxy S9 navigation bar (read on).
As shown above, once you disable the show and hide button, the dot is gone.
Now Galaxy S9 navigation bar is locked. And you cannot manually hide the navigation bar and navigation buttons.
Please note that some apps may enter immersive full-screen mode automatically. Under this mode, the navigation bar and navigation buttons are hidden automatically. You cannot lock navigation bar in this case.