You cannot use TurboTax Online to file for past years. To file for earlier years you have to use the CD/Download TurboTax software for each year that you need. You can purchase downloads at the following link.
You might get a better price from a reputable online seller that still has TurboTax in stock for the years that you need.
Tax returns for past years cannot be e-filed. You will have to print your past-year tax returns, sign them, and file them by mail. Mail each year in a separate envelope.
Don’t forget your state.And you will have to print and mail your returns. So be sure to attach copies of your W2s and any 1099s that have withholding on them. You have to mail federal and state in separate envelopes because they go to different places. Get a tracking number from the post office when you mail them for proof of filing.