I would love to include the Account Summary on my clients' invoices. Is it by project or customer?

Good to see you here in the Community space, Dawn. Allow me to share some insights about your issue on invoices.

When you have multiple projects associated with one customer, you can add an account summary, which will also display an overview of all the projects linked to that customer, not by individual. 

If you want to add the account summary to a specific client only and not include the associated projects, I suggest sending feedback to our product engineers for them to look at this. They are responsible for adding new features in future updates.

To send your request:

1. Go to the Gear icon.
2. Select Feedback.
3. Enter your comments or product suggestions.
4. Tap Next to submit.

After sending the invoice to your customer, you'll need to receive and record their payments in QuickBooks Online.

If you have any questions about customizing your invoices, please don't hesitate to ask in the Community. We're always happy to help. Stay safe!

I have expressed my disappointment many times with many aspects of the progress invoicing component of QBO via Feedback.   It just doesn't make any sense at all for me to be given the option to provide a Customer Summary for a customer with multiple projects.