Delighted to have you here in the Community, @contact-irwinbla. I’ll help you with changing your bank account number on an invoice in QuickBooks Online (QBO).

When creating an invoice, let’s make sure that we’re using the correct template to be sent out to the customers. To change the bank account number, we can edit the template by following the steps below:

1. Go to the Gear icon.
2. Under Your Company, select Custom form styles. 
3. Choose the template you are using in your invoice, and click Edit.
    
   
   
   
4. Select the Content tab.
5. Click the pencil icon on the third layer of the invoice layout.
6. Enter the corrected account number on the box below the Message to customer on.
7. Then, select Done.

You can also add the corrected details by going to the Emails tab, and entering the details under Message to customer. Then, click Done.

For further assistance with customizing transactions, you can always hit the Reply button. The Community always has your back. Have a great day!