Thanks for visiting the QuickBooks Community, @pressurewavellc-. I've got some steps to help you add a pay invoice button in QuickBooks Online (QBO).
First, we need to ensure that your QuickBooks Payment is active and connected to your QBO account. Then, we can go to settings and activate the pay button on your invoices.
Here's how:
Go to the Gear icon and choose AccountsandSettings.
From the Sales tab, tap the Online delivery section to edit.
Check the box next to "Payment options" to enable online payments.
Click on "Customize look and feel" to further customize your invoice template.
Scroll down to the "Action" section and check the box next to "Pay Now" to include the button on your invoices.
Click the Save button. Then, hit Done.
Additionally, you can visit these articles for further instructions on how to include additional details or personalize sales transactions: