Cnfused concerning form 1095-A, or 1095-B. unable to go back to the return to correct the mistake.

If you have not e-filed the return, you can go back to correct or edit the return prior to filing.

1095-A is the only form required to be filed on the return.  If you had Marketplace insurance.  1095-B is not required to be filed.

Here is how to enter form 1095-A into TurboTax:

1. Click on Federal Taxes (Personal using Home and Business)
2. Click on Deductions and Credits.
3. Click on I'll choose what I work on (if shown)
4. Scroll down to Medical.
5. On Affordable Care Act (Form 1095-A), click the start or update button.

Or 

Search form 1095-a in the search bar in the upper right corner.  Then hit "Jump To"

@Soledad