Ask the patient to hold the front of the headset, while you tighten the screw at the back so that it doesn’t slip down their face. Help them adjust it for comfort.
Ask if the login screen is clear. If not, they can try:
Adjusting the headset on their face
Adjust the lens inside, by moving the lenses closer or further apart.
If they can’t see the login screen directly in front of them, ask them to try recentering, by doing a long press of the Home button.
Put the controllers in their hands, ensure they are holding it properly with their index finger on the trigger button.