Remember that the design of the headrest is to prevent injury in the even of an accident, not to allow you to comfortably rest your head back as you drive down the road.
Since you have had a previous neck injury, maybe there is still an issue with your neck, that you have been ignoring. With the headrest turned around, if you have an accident, I bet that your bad neck will suffer an even worse injury.
What you should do is get yourself to either a chiropractor or to an orthopedic doctor, and have them inspect your neck and shoulders, look at how you’re sitting in your car, and make suggestions or adjustments to you in order to get you comfortable in your new car.
BC.