You can preview you 1040 by logging into your account and entering you return.
- Once in your return click My Account > Tools.
- In the Tools Center click View Tax Summary.
- Next page along the Tax Timeline you'll see Preview my 1040.
You can look over your 1040 here, to edit the 1040 you'll need to go into the sections of your return that affect it directly, Personal Info and Federal Taxes.