How do I customize controls, button layout, firing modes and sprint mode?

Everything is on the Controls & HUD tab.

HUD Layout

• Control Buttons → Edit — a visual editor where you drag, reposition and resize all on-screen buttons. Available from the lobby only.

• Floating Joystick — on/off.

Battle Aim Assist · Auto ADS on Fire · Auto Reload · Assistance in Mining · Camera Rotation on Attack / on Aim / on Actions

Shooting and Movement

• Sprint Mode — Button / Hybrid / Swipe

• Crossbow Firing, Shotgun Firing, Rifle Firing — each can be Tap / Hold / Release, so you can set a different firing style per weapon type.

Interaction

• Show Old Interaction UI — reverts to the previous interaction menu style.

• Double-click to Move Items and Double Click Delay — move an item by double-tapping it, and adjust how fast the second tap has to be.

Everything except the button editor can be changed during a match from the pause menu.

Camera and aim sensitivity is on its own tab — see "How do I set up sensitivity and gyroscope aiming?".