DIAGNOSIS You're not using it wrong—the 4-way joystick/navigation button takes some getting used to. It's stiff by design to prevent accidental presses, but the directionality can feel confusing.
FIX Think of it as a tiny joystick, not a button. To open the menu, press it straight in. To navigate, tilt it in the direction you want to go: left, right, up, or down. To select a menu option, press it straight in again. It requires a deliberate touch. Practice by tilting it slightly—you'll feel it click into directional notches.
IF THAT DIDN'T WORK Make sure you're pressing the joystick itself and not the plastic ring around it. Your finger should be centered on the small nub. If it feels stuck or unresponsive in a specific direction, there's a small chance debris got inside. With the monitor off, try gently blowing around the base of the joystick with compressed air.
HEADS UP The menu will often wrap around. If you go past the option you want, just keep tilting in the same direction to loop back to it, rather than trying to reverse direction precisely.