Default Sales/Use Tax Applicability on a voucher

Hi there,

 

 We are using PeopleSoft 9.1. I am creating a voucher using the PO, I brought in the PO item however I want the “Sales/Use Tax” (see screenshot)  to be defaulted to “Sales/Use Tax Applicability: = Sales Tax Applicable” where do I set this up? Please advise.

Thank you,

Dante