I've got your point, userluminantremodeli.

I understand how important it is for you to have complete control over the information your customers see on the invoice. It isn't possible to prevent your customer from viewing the invoice after it has been sent. They will be able to access and read it once you deliver the information to them.

In the meantime, you can control the invoice that appears in your customer emails. You'll have the option to customize your invoice template to show only the amount and due date. I'll show you how.

1. Click the Gear icon, then select Custom form styles.
2. Locate the invoice template that you use, then choose Edit.
3. Select the Email tab, then checkmark the Summarized details in the How your invoice appears in email.
4. You can also leave the PDF Attached unchecked to prevent your customer from seeing the full details of your invoice.
5. Review the email message template and make necessary changes based on your preference.
6. Once done, hit Done.

For your reference, feel free to visit this article for more details: Customize invoices, estimates, and sales receipts in QuickBooks Online.

The idea of preventing your customer from accessing the invoice is great for future product enhancement. I encourage you to send your product suggestion inside QuickBooks by going to the Gear icon and selecting Feedback.

In addition, I've added this link to guide you in recording payments for future use: Record invoice payments in QuickBooks Online.

If you need further assistance with managing invoices in QuickBooks, let us know. We're always here to help you.