Players can only set their gender when they first create their player profile. After that, they may change their gender from unknown to male or female at any time. However, once a player's gender has been set to male or female, the player cannot change it themselves.
If a change is needed after that point, the club or the player can contact Nettla with the email address of the player whose gender should be changed, and we're happy to help out in those moments.