I got hit by a car and it damaged the front wheel and fork. I took my bike (canyon inflite AL) into a store and they ordered a replacement fork and wheel. The problem is they had to replace one of the internal bolts in the headset because it had been stripped in the crash. I keep trying to reset the handlebars to be centered and they feel centered for a bit then it seems like they are off again. Has anyone else had this problem or have a solution they'd propose?
Presumably what is happening is that the stem bolts are not providing enough clamping force of the stem onto the steerer, and the stem is moving off center. You can check the alignment of the stem and wheel by looking down on then from above. The stem being mis-aligned should be obvious.
There are no 'internal bolts' in the headset, so you may mean either the steerer tube expansion plug or one of the stem bolts. If one of the stem bolts was stripped the thread in the stem may also be damaged.
Try making sure the bolts are tightened to correct torque (should be printed on the stem). If a bolt will not tighten to that torque the stem thread is damaged and you need to replace the stem. You can also try a carbon installation compound that helps grip carbon components.