You can generate, customize, and filter a Sales by Customer Detail report to export your customer's invoice product line items into Excel, Goodx International Limited.

While QuickBooks Online doesn’t currently offer the option to directly export invoice product line items to Excel, we would appreciate it if you could share your feedback with our developers for consideration in future updates.

In the mean time, you can customize Sales by Customer Detail report to meet your needs.

Here’s how:

1. Navigate to Reports and choose Sales by Customer Detail.
2. Set the Report period to cover the customer’s invoices.
3. In the Columns section, select the columns related to invoices (e.g., Customer, Transaction Type, Product/Service, Memo/Description, Quantity, Sales Price, and Amount).
   
4. Click Filter.
   
5. In the first dropdown, select Transaction Type, and in the third dropdown, choose Invoice.
6. Click Add another filter and select Customer in the first dropdown. You can either choose a specific customer in the third dropdown or leave it blank to include all customers.
7. In the Group by section, choose Customer from the dropdown.
   
8. Click Export, and then select Export to Excel.
   

This customized report provides detailed transaction insights from invoice line items, along with totals organized by customer. Additionally, you can save this report for quick access in the future if you need it again.

Let us know if you have further questions.