You've come to the right place, @carla9.
You can run the Profit and Loss Detail report. This report allows you to drill down to cost of sales by invoice with ease.
It's also a great idea to modify your report to focus on the details that matter the most, check out these links:
If there's anything else that I can help you with, please let me know in the comment section down below. I'll be always around ready to help.