Head support is offered for baby size carrier only. If you are using the head support make sure that the airways of the baby remain free. Make sure that the head support is not too tight, there should be room for head movement.
For the smallest babies turn the head support inside the back panel and fixate it with the push button.
For bigger babies you have 3 fixed positions or due to the soft wrap like structure of the head support and the push buttons on different positions you can use a combination of these positions.
If you need a tighter fit you can fold in the head support on the sides and fixate it on the push button of the inside panel. But always make sure the head support is not too tight and there is enough room for head movement.