I appreciate you for stating your concern clearly. tsd81.

In most cases, you received an order from one of your customers, and the goods are not in stock. You want to create a purchase order directly from the sales order to buy the goods from a vendor. 

When doing this, the system will use all the information from the sales order. QuickBooks will think that the transaction is billable since you’re ordering the items to complete the customer’s order. This is the reason why it automatically reflects as chargeable to the customer from the sales order. 

This behavior is completely how QuickBooks was designed to interact in this situation. If you’re ordering items not just for this customer, you might want to create a separate Purchase order. Here’s how:

1. Click Vendors at the top. 
2. Select Create Purchase Orders from the drop down menu. 

Stay on communicating with us if there’s anything else you need.