Steamdeck controls

Recently i tried to play poe1 on steam deck and noticed that button setup really uncomfortable, like there is no option to change setting at all and using combo like (L3 + <-) (joystick and left arrow) is really disgusting, why there are no options for buttons like l4/l5/r4/r5 (back side buttons)? Also would be nice use that keys for teleport scroll or hideout macro or some utility skills etc.