Can I make a correction to a completed, but not yet mailed return?

[DoninGA]

When you sign onto your online account and land on the Tax Home web page, scroll down and click on Add a state. 

This will take you back to the 2020 online tax return to make changes to the tax return that has not been filed.

[usercurt-anderson]

The reply was not helpful. I worked with a customer service representative and she was not able to help me either.