If you completed the 2016 tax return using the online editions, then you will have to download the 2016 tax data file so that can be transferred to the 2017 tax return.
To access your current or prior year online tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/
Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. Click on the Year and Click on Download .tax file
See this TurboTax support FAQ for transferring the tax data file - https://ttlc.intuit.com/questions/1901506-transfer-last-year-s-return-to-2017-turbotax-for-windows
