They aren't supposed to, but if you submit the scores, the university can use them along with your GPA, SAT/ACT, etc. to determine admission. If you don't get at least a 3 on an exam, you aren't going to get college credit, so one option for you is to simply not submit your scores. On the other hand, college admissions staff know the only reason a student wouldn't submit their score is because it is low. Another issue you have to consider is that someone earning an A or B in an AP class should be earning a 5 or 4 on the AP Exam. A lower test score calls into question whether or not your high school generally grades easily or inflates grades.
Talk to your guidance counselor about all of this and decide what is the best course of action to take.