We don't yet understand what you are doing. You specifically mentioned a 2015 return in your question above, but online TurboTax is currently only for a 2016 return.
Are you preparing a 2015 return? If so, that can only be done by purchasing desktop software (CD/download), as VolvoGirl mentioned above, and installing it on your computer. Then you would need to download the *.tax2014 data file (if it was prepared online) in order to transfer it into the 2015 return.
