Is there an option to turn off sending a pdf copy of the invoice to the customer?

Hi there, @brittney5.

Yes, there's an option on how to turn it off. Just uncheck the box beside PDF Attached under Online Delivery. I'll show you how:

1. Go to the Gear icon.
2. Select Account and Settings under Your Company.
3. Select Sales under the Account and Settings window.
4. Click the Online Delivery pencil icon.
5. You unchecked the box beside PDF Attached and select an email option for invoices under Additional email options for invoices.
6. Click Save.
7. Click Done.

You may check this article for additional reference: Email sales forms directly to your customers from QuickBooks Online.

In case you want to add attachments to your transactions and customize them, just click these articles for reference: 

• What transactions can keep attachments?
• Customize invoices, estimates, and sales receipts in QuickBooks Online

I'll be right here to assist you if you have any other questions or concerns. Just leave a reply below. Take care!