Thought I would answer my own question. You can only change #'s that appear in blue. If the # is black, it's coming from either a worksheet or another form.
Example: I was trying to change gross receipts directly on the Scd C. Didn't realize that this # comes from the Schedule C "Worksheet". When I went to the worksheet, I was able to change the #.
Take away lesson: TT is designed with the assumption that most people will use the "step-by-step" mode. I prefer "forms" mode but I now see that, except for simple returns, it can trip you up.
