Hello there, @godwin2. When creating purchase orders in QuickBooks Online, you can opt for either the Category or the Item option. Choose one based on your tracking requirements, as using both fields simultaneously is unnecessary.
The Category details option allows you to classify the purchase order under specific categories, which helps organize and track expenses across different types of purchases.
On the other hand, the Item details option lets you specify individual products or services. It includes detailed descriptions, quantities, and prices.

The Cost of Sales account did not appear when selecting the Item details option because this field is specifically used for products and services.
Please know we're unable to suggest a specific category for your transactions. In this instance, I recommend consulting your accountant for additional guidance on selecting the appropriate account.
After creating your purchase order, you add it to expenses, bills, or cheques.
Utilizing these options correctly ensures accurate record-keeping and enhances inventory management. Reach out anytime if you have any other concerns. We are here to help.