Thank you for posting here in the Community. I can provide some clarification about the categories in QuickBooks Online.
Currently, the option to set up an expense account for a product category is unavailable. However, you can add it to the purchasing information of the service item.
The categories groups your products and services when you run sales or stock reports. You can use the Sales by Product/Service Detail report to track the profitability.
Please follow these steps to run the report:
For additional reference, I've attached a link you can visit for tips about how to handle categories when running reports: Group your products and services into different categories.
Feel free to hit that Reply button if you have further questions regarding the sales categories in QuickBooks. Have a great day ahead.
Thanks for coming back, usermattdeacon.
I appreciate you performing the recommended steps provided by one of my colleagues. This time, let me help you figure out where you can check put a checkmark in the box.
If you are referring to the I purchase this product/service from a vendor or supplier, it is located at the bottom under Purchasing information. See the screenshot below.
Please let me know how it goes or if you have any follow-up questions. I'll be here if you need further assistance. Just leave a comment below.
Thank you for the follow-up reply, and I appreciate you for sharing the screenshot of your service item. I'm here to guide you along the process so you can tick the desired box and track the profitability accordingly.
Based on the image added, I can see that you've access QuickBooks using a mobile application. To mark the box under the Purchasing information section, I recommend logging in to QuickBooks using a supported web browser.
Once done, follow the steps provided above to mark the I purchase the product/service from a supplier/vendor box.
For more tips about handling your items or products and services in QuickBooks Online, you can open this link: Add product and service items to QuickBooks Online.
You can also group your items into categories to keep them organised. Here's how: Group your products and services into different categories.
If you have any other follow-up questions about ticking the box under Purchase information, let me know by adding a comment below. I'm always here to help. Have a good one!