I am a short person and when I buckle up, the seat belt cuts into my neck. I saw an ad for an item that would help the situation, it was $3.99. Being frugal I thought there must be something as good and less expensive.
I went to the dollar store and bought a package of medium length bungie cords. I put one end around the door pull, tied a knot about 1/3-1/2 way, hooked the hook through the center of the knot. That left the other hook which I can hook around the seat belt. It pulls it down and away from my neck making it more comfortable to wear.
I am a tall person and have the same problem. I bought a device at Wal Mart that does the trick (it was ($9.99), but I could have made it myself, or used a rubberband around the two parts of the belt.