If you already filed, you will need to wait for your return to either be rejected or fully processed. If rejected, then you can make whatever changes are needed and file again.
However, if the return has been accepted then you will need to wait until it has been fully processed before you can amend and make changes.
If you have only printed your return and not filed, then run the Review again to correct any issues that you may have missed. Then proceed with filing.
@PaulaM What if he printed to File, rather than printed from the print center? In that case wouldn't the return be locked out from further TT edits other than amending the return after it was mailed and approved?
In other words, isn't the return "finalized" as far as TT is concerned once it's printed from the "File" menu?
No, not at all. A return is not filed until you transmit via efile or physically mailed a paper return. Once you have done that, then no changes may take place without an amendment.
You can view,print, save a file at anytime once you have paid for the preparation of the return. Viewing, printing, saving a file is a separate function from filing. And you could do all of that multiple times at different points, although I don't see the point of that.
However, the only version that would be relevant is the one that was actually transmitted or physically mailed in. @crash12_mn