There are a variety of sales reports in QuickBooks Online (QBO) that can provide the unit or quantity of the product or service that your customer bought in a transaction. One of the lists is the Sales by Product/Service Detail report. You'll have to pull it up twice and make sure to set its Report period to This Calendar Year-to-date and the other one to Last Calendar Year-to-date. This way, you're able to compare your sales from last year to this date. Let me guide you how.
Go to the Reports menu.
Type in Sales in the search box, then select Sales by Product/Service Detail.
Set the date to This Calendar Year-to-date or Last Calendar Year-to-date option in the Report period field.
Select the Customize button to filter other information you need.
Click Run report. Repeat the process as necessary.
I've attached a screenshot below that shows the outcome after performing the steps above.
After that, you can save its current customization settings. This way, you're able to pull up the same report setup in the future. For the step-by-step guide, you can refer to this article: Memorize reports in QuickBooks Online. It also contains instructions about exporting to Excel and editing/deleting a memorized report.
Additionally, you can use reports to get helpful insights on the things you buy and sell, and the status of your inventory. To see your best sellers, what's in stock, and still on order, I'd recommend checking out this article: Use reports to see your sales and inventory status. It also includes instructions about customizing your reports to get the info you need the most.
Please know that you're always welcome to comment below if you have other concerns or follow-up inquiries about managing your sales transactions in QBO. I'm just around to help. Take care.