I want to print the history of ONE customer. The invoices we've sent and the payments hes made, how do I do that?

Printing customer transaction history is easy, @kjvillasenor.

You'll want to go to the Sales menu and print your customer transaction history form there. Let me guide you how.

In your QuickBooks Online (QBO) account:

1. Go to the Sales menu.
2. Select the Customers tab.
3. Locate and select the Customer's name.
4. Select the Transaction List tab.
5. Click the Printer icon to print preview the sales transactions. 
6. Make some adjustments if necessary and click Print once done. 

Also, check this great article that provides detailed information on how to customize your invoice in QBO: Customize invoices, estimates, and sales receipts in QuickBooks Online. From there, you'll learn how to personalize your invoices and bring a unique look to your company.
 
In case you have other concerns or questions, you're always welcome to post here anytime. I'm more than happy to work with you. Stay healthy and keep safe.