It is not possible to adjust the booster seat from the upper position to the lower position. From the upper position, the booster seat must first be fully lowered into the seat cushion, and then folded up to the lower position.
Pull the handle forwards to release the cushion.
Press down with your hand in the centre of the cushion in order to lock it.
Check that there are no loose objects (e.g. toys) left behind in the space under the cushion before lowering.
Before the rear backrest is lowered, the booster cushion must be lowered first.