I’m working my life away on my NYU application, it’s my #1 choice school. I’m a bit confused about the testing policy, though. I had already submitted my SAT score, but am I also able to submit an ACT score in case my ACT is a higher percentile? Can and should I submit both? I got a 1380 twice on my SAT with a superscore of 1400 and my highest ACT is 30 (superscore is also 30). Or can I also submit AP scores instead? I have 4 AP tests (APUSH, WHAP, AP Stats, AP Psychology) I’ve received 5s on and 2 I got 4s on (AP Lang & AP Human Geo). I am planning on applying to Stern. Any replies/tips would be greatly appreciated! 
Thanks.
You cannot substitute AP scores for the SAT/ACT. You can certainly submit both. Generally speaking, they will give weight to the higher score.
Submit the scores that best support your application. NYU maintains a flexible testing policy, so you may submit APs in lieu of the SAT or ACT. Most people choose to send one test or another. For example, I submitted my 1400 SAT, not my 31 (superscore) ACT. Sending both is sometimes too much.
If you are interested in Stern and opt to submit your AP examinations, one must be mathematics.
If you want to submit your AP exams, the Statistics, Psychology, and either history will suffice.
In my honest opinion, the SAT / ACT gives more depth to your application, and I would advise you stick with one of those two tests. You should self-report your AP scores on your common application.