I’m trying to do my second tax form from 2019

The online product can only be used to prepare and file one tax return. If you are trying to prepare a return for another person, you must create a new account and pay again for that tax return.

If you are trying to file a second tax return for yourself because you left something out of your first tax return, you can't do that, You can only file one tax return. A tax return that has been filed and accepted but is missing something must be amended using form 1040X. The amended form is not yet available and you should not amend until you have received the refund from your original return. 

Here are instructions for amending a return: https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed