I am on the Check This Entry page, and the number of my Elective Deferrals, box 12 b, is too high. But, the screen will not allow me to fix it.

[Anita01]

To make a change on a W-[2, type W-2 in the Find window, hit enter, then the Jump To.  Go though to the little summary that shows all your W-2s, edit the one you want and make your change.

[frederickbp]

That tells me how to change the W2 data; if I do that, then the info in TurboTax is different from what my employer sent the IRS, so I would be audited for certain. There are steps one should take in this scenario that it would have been helpful if TurboTax had told me to do. Given that they are time-sensitive, it would have been especially helpful if they had told me this when I entered my W2. Finally, from a software perspective, showing me a box, highlighting that there is an error in it, and allowing me to edit the contents of that box suggests that I can fix it then and there, but I can't. Worse, the software should have told me to do what you typed in your answer above -- that's not the right answer, but at least it is not an infinite loop.

[Anita01]

By saying the screen would not allow you to fix it implies that the number you entered was incorrect and you indeed wanted to change it.