Q: iPhone camera records bad audio

I was wondering if anyone can help me with an issue I'm having. My iPhone 5s on iOS 9.0.2 isn't recording audio very well, the video is fine but when you play it back its very quiet even at full volume. But when I record a video in snapchat of the same thing, it's perfectly fine. I had no phone case on at the time so no microphones were covered and I made sure to hold it so that I didn't cover any either.