Can anyone tell me how do I change the screen safe on SP mobile?

I got a new phone about 2 days ago, and I was pretty happy. But when I got to SP, I realized something... I can't press the countermeasure, gun, and fire weapons button using the edge of my thumb. Which is my most comfortable way of pressing something. Either I press it in the edge of the button, or I put my entire fingerprint on the button. Anybody know how to change that? Like some sort of screen safe area thingy?

FYI: Phone is a Samsung Galaxy A03S. It's honestly not too different in terms of performance, but it's still good enough.