MINI 3 pro headlesss setup

Hi, I have read (googling) the mini 3 pro has a “headless” option. how to set it up. I have 9 drones homemade with headless switch on the RC. HEADLESS in other word let the controller give you the option to compensate your move based on beginning position. When orientation moved by 180° horizontally moving the right stick (mode 2) to move right (stick to the right) the drone effectively move right, ie. Direction automatically adjusted by + 180°. Without headless on move the right stick to the right would have let the drone move left . How to set the HEADLESS ? Thank you before hand for your help.
B rgds - Thierry (BE)