I need a Purchase Order number immediately is automatically checked for a specific user

Hi,

Asking assistance what triggers the checkbox for 'I need a purchase order number immediately' is automatically checked after clicking view cart and checkout.  And then when checkout button is clicked, a message error 'A Purchase order number cannot be assigned because none of the requisition lines has an active supplier and supplier site'.  Actually, we are using a catalog with no supplier site assigned to avoid other suppliers from being checked-out.   This only happens for one user as of the moment.  We are using Internet Procurement 11.5.10.2

How to uncheck this checkbox.

Thank you in advance.

Best regards,

Angel