Hi ,
I found those links from Samsung website, hope they are helpful for you.
From the camera, touch Switch to switch between the front- and rear-facing cameras.

http://www.samsung.com/us/support/answer/ANS00046743/
http://www.samsung.com/us/support/answer/ANS00050621/
As you are using a Samsung device, we suggest contacting Samsung support if you need further assistance, it is their responsibilities to provide support for their own product. I think they are the best resource to help you.
Best regards
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