You've come to the right place, @BeccaW.
There's currently no option to edit an invoice after it is sent to your client. However, you can manually update the existing invoice and re-send it. Here's how:
You can also check out this article to learn more about managing your customers and income in the program.
That's it. Feel free to post again here in the Community if you have other concerns, @BeccaW. I'm here to help.