Yes, so long as you haven't filed yet, you can change your return as much as you need to.

Use the navigation menu across the top of your screen to navigate back to the spots you need to make changes in.

I can't do that. I checked the box that I would send a paper return, so I think the system considers my return as having been filed. Is there any other way to go back in and edit it?

You should be able to, as you can always choose to go back and NETFILE even after you've printed your return to mail. Do you not see the navigation menu across the top of your screen?

how do i edit a name spelling mistake