I've used TTax for years. Due to tax law changes, I tried the free version. Don't like it plus have loss c-forwards. Want to start over with paid version. How do I?

You don't need to start over.  What you go to the section of the program where the carry-forwards will be reported.  Once you enter this section of the program, TurboTax Free will state that to enter the information you will need to upgrade to the paid version that is used to report that information (like Premier, for example).

For example, if your carry-forward losses are Capital Losses, you can type the word Schedule D in the Search box (up in the upper right hand corner with the magnifying glass).  You will receive a Jump to Sch D link, and, when you click it, you will enter that section of the program.  To continue in that section, TurboTax Online will prompt you do upgrade to continue entering the information.