Why can't I correct Schedule E's box that needs to be unchecked???

Try going to the forms mode and check box NO in...

Complete For All Properties

Did you make any payments that would require to to file Form(s) 1099?  

Forms Mode lets you view and make changes to your tax forms "behind the scenes."

To switch to Forms Mode, open your return and click the Forms icon in the upper-right corner of your screen (or choose Forms from the View menu at top).

The 1040 Worksheet will display and all the forms in your return will be listed on the left side. Simply select a form to open it.

To switch back to the interview, click the Step-by-Step icon in the upper right corner, or choose it from the View menu.