All my AP exams have been good so far (4’s and 5’s) with the exception of one 3 in AP Physics 1, which I got in my sophomore year. Should I report this exam to selective schools as an intended CS major? I’ve heard some say to simply omit it, whereas others claim that not sending it could make colleges assume I did even worse. Will reporting it be significant? If it helps, I got A’s both semesters in the class and made 4’s and 5’s on all the practice exams, I just choked a bit 
Bump
Are you talking about not listing them on the Common App or not sending the actual score report to the school? If I recall correctly, the College Board score report automatically contains all scores, and you have to specifically ask (and pay) for a score to be withheld… Most schools only require that you self report the score on the Common App so you could leave it off the application. Both of my son’s each had 1 AP score that was a three, and they just included them. Figured that it was better to be transparent. Now, if you wanted to be a Physics major, I would have different advice. Others may disagree so see what feedback you get.
Also realize that colleges don’t really use AP scores for admissions. And getting essentially a C in AP Physics as a sophomore isn’t a catastrophe. Most people take AP Physics as a senior.