This is my recommendation:
1. Open configurator in editing mode.
2. Go to Actions/Test Inputs
2a. Make sure "cTextBox" input is visible.
3. Start configuring - keep an eye on "cTextBox" to see exactly when it changes from blank to "6".
4. As soon as it changes, you will know which input on leave statement is filling it in.
The 2 caveats to this are:
A. If you run through a whole "test inputs" scenario, and the text box stays blank, then you should check page on leave codes, as the code will probably be sitting in there.
B. It may be possible that more than one input has code which sets the value for "cTextBox". After I make any big code update to a configurator, I always test mutiple configurations to make sure the MOM is still coming out correctly. I set up lots of lines in quote entry and use a testing script which tests many/all of the possible permutations. This is the most accurate way of quality-checking your code.