Hi,
You have a syntax error in your change script, click the check syntax errors button in the script editor toolbar,
So, you have three cases where you have a string literal with an embedded double quote, so you either need to use a single quote in those cases or escape the double quote with a slash, that is;
case "* BASIC Clipboard (5.25 x 13.5\")":
For the Sales Tax and Total fields In the display patterns dialog you can select "Allow Zero" which will display blank when the value is zero.
Regards
Bruce