Do you possibly have more than one TurboTax account? Many users do and just don't realize it. In order for your prior year's pertinent info to transfer in automatically, you must use the EXACT same account (same username and password) that you used when filing for 2015. To see if you have more than one TT account, see the instructions below.
https://ttlc.intuit.com/replies/3302270
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***