How do I customize the message to customers that is shown when you click on "Print or Save Invoice" in the email message?

I hope you're having a great weekend, dawnjohnson.

I'll show a way where you can customize the email message for your invoice.

You can either go to the Sales settings or edit the default template for your invoices.

For updating the message in the settings, here's how:

1. Go to the Gear > Account and settings. 
2. On the left panel, click Sales.
3. Go to the Messages section and edit the Email message field. 
4. Hit Save and then Done. 

To edit your invoice template, you can follow these steps:

1. From the Gear icon, select Custom Form Styles. 
2. Click the Edit link of the default invoice template. 
3. Click the Emails tab, and edit the Message to customer field.
4. Hit Done.

To learn more about editing the customer messages or customizing the sales forms, you can read these articles: 

• How to set up or change customer messages
• Customize invoices, estimates, and sales receipts in QuickBooks Online

If you have additional questions about the process or other concerns, please feel free to reply on this post. I'll get back to you as soon as I can. Stay safe!