SO Sales Tax on line item as Check Box vs. Selecting the Tax Code AND How to Default to Not Taxable

I am having a couple of issues with Sales Tax by line items on sales orders.  I remember in a past life that the Taxable / Not Taxable was a check box on the Sales Order line item.  For a new customer of mine it is displaying as a drop down where they always need to select a tax code.

That would normally not be an issue if the line defaulted to the correct setting for each line.  The customers are all marked as Not Taxable and all my Items are marked Not Taxable as well yet we have to select the tax code every time on every line.