In the Options > Touch Controls menu, you can adjust the size of the on-screen controls and choose between a fixed or floating joystick (visible or invisible), as well as enable or disable auto-movement and hide the up/down buttons for swimming.

You can also set the scanner behaviour: instant (as on Subnautica mobile), or original (same behaviour as on Subnautica PC).

Finally, you can choose a button style (opaque, transparent, icons) and adjust the camera speed.

Please note that you cannot change the location of the buttons on the screen, except for the joystick.