The setup experience will also ask you if you want on-screen or capacitive buttons, but that's only the start of the navigation customizations. Find the Buttons menu in system settings if you want to switch between on-screen and capacitive buttons at any time. When you are using on-screen buttons, there aren't many settings to toy with—you can swap the back and recents button, and that's basically all you've got.
If you choose to rely on the capacitive buttons, you can set long-press and double-press actions for the back, home, and recents button. For example, you can configure a double-press of the home button to put the phone to sleep or a long-press of recents to open the previous app. The home button is also the fingerprint sensor, of course, but the other two can be swapped just like you can with the on-screen buttons. They're just backlit dots on the bezel, so the action you assign is entirely arbitrary.