The purpose of the headrest is to stop your head rotating backwards. In order to set the headrest to you, you want the pointy bit at the back of your head to match up with the middle of your head restraint. The pointy bit is more correctly known as the occipital bone.
Your seatbelt is part of your vehicle’s passive safety system and in modern vehicles, you’ll find a 3 point lap and diagonal system which are specifically designed to contain you within your seat in the event of a collision. In an accident, anyone or thing that is not restrained will be thrown forward at the speed the vehicle was doing at the time of the collision.
If you hit a stationary vehicle at 30 mph anything or anyone not restrained will hit what is in front of them at 30 mph, a terrifying thought! For the driver, this will be the steering column and for passengers in the back, this will be the people in the front. Seat belts are designed to bear upon the bony parts of your body. This means the lap part should be across your pelvis and the diagonal across the chest and shoulder.
When using a seat belt, make sure to give it a tug (every time) to ensure the reels are working. Examine by a feel and a glance for cuts, tears and frays and always check the tongue is secure.