Has to be how you're sitting. There are three separate switches to adjust the seat - depending on trim level - and also another switch to control your pedal position (on the steering column), and then a lever to control the steering wheel tilt. Shoulder/neck pain is caused by improper angle of your head while viewing the instrument cluster or having to move it constantly to see the cluster, or bad angle of the seat (usually too far back). When you make adjustments, do it without additional cushions or anything else - you want to adjust the seat first.
1) Adjust seat back so that it is as straight up/down as possible, so that your shoulders are directly over or slightly behind your hips. This can be uncomfortable at first, but keeping your shoulders as close to being directly above your hips will help eventually.
2) Adjust the seat height so that when you look straight ahead, you see only the top of your dash, but can move your eyes down and see the instrument gauge cluster - without tilting your head down.
3) Now - if your truck is equipped with 8-way adjustment on the seat, bring the front of the seat up/down a little, and the back up/down a little, then readjust the seat back - again, trying to maintain a shoulders directly above or slightly behind your hips. The point of this is to support the thighs and buttocks, while maintaining proper posture, and at the same time not putting too much pressure on your knees, buttocks, or lower lumbar.
4) Adjust your steering wheel to where it is comfortable. You will probably NOT be able to see the top of the cluster (turn signals, and a couple of other indicators - but this is fine.) Ideally your elbows should be slightly in front of your body while your hands are at the 10 o'clock and 2 o'clock positions on the steering wheel.
5) Slide your seat forward/back so that your feet just reach the pedals while at the same time maintaining 4) above - you might need to play with these two points until you are comfortable.
6) If your pedals are adjustable, combine with 4) and 5) above: you want your feet to be able to reach the pedals, with your legs at a comfortable angle, but NOT have to draw your knees up, while your heel is resting on the floor. When you push the pedals with the ball of your foot, it should be a simple rotation motion at the ankle.
7) Lastly, if you have lumbar adjustment, you'll need to pump it up from time to time to provide support to the lower back (It's an adjustable air pillow).
The biggest thing is to maintain your shoulders above your hips as much as possible, with your elbows slightly forward while your hands rest on the steering wheel, and minimize movement of your head while shifting between viewing the road and the instrument cluster.
If your seat has memory, set it by pushing the center button on the memory switch, then push the 1 (or 2). If someone adjusts your seat and you need to get back to your setting, just push 1 (or 2) the next time you start your truck, before you begin driving.
It can take a while to get used to this - but it will help.
