How do I get the scan code or link to pay electronically on my customer invoice. I have it on a couple customers but now i cant find where it will let me add it for them.

Hello there, lbatten. 

QuickBooks Online Payments is a great way to provide the payment link option on customer invoices. I'd be happy to provide you with the steps.

1. Navigate to the Settings ⚙ icon and choose Account and settings.
2. Click on the Sales tab.
3. Under Invoice payments, click on Edit, then choose the desired payment options.
4. You can also enter Payment instructions. 
5. Save your changes by clicking Save.
6. Select Done.

Another way to ensure the customer gets the Pay now or payment link is to enable the Online payments directly from the invoice window.

Also, I'm adding an article that provides instructions on generating customer statements to show summaries of their invoices, payments, credits, and remaining balances: Create and send customer statements in QuickBooks Online.

Keep me posted if you need further assistance managing your invoices in QuickBooks. I'll be here to provide you with the support that you need. Keep safe.