After update this happened. QB put an unknown person's banking info on our invoice. Went out to customer who deposited to that bank and not ours. We are out $4200!

I'm here to help rectify the issue where an unknown person's banking information appeared on your invoice after the QuickBooks Online (QBO) update, John. 

I encourage contacting our Support Team firsthand. They can help trace the changes with the banking information in your invoice following the update. Here's how to contact them: 

1. Sign in to your QBO.
2. Select Help (?) at the top right.
3. Select or type Contact Us.
4. Enter your concern, then select Let's talk.
5. Choose a way to connect with us:
   • Start a chat with a support expert.

To recover the lost customer payment, consider reversing the transaction. Please communicate to your customer that you're reversing the transaction for this. Then, refer to this article for a detailed guide to the process: Void or refund transactions in QuickBooks Payments. 

After reversing the customer payment and before letting the customer pay the invoice again, please also ensure to update your bank account first. 

When resolved, I'm adding this article about categorizing transactions in QBO as a future guide: Categorize online bank transactions in QuickBooks Online. 

If you have any updates about recovering the payment in QBO, we'll be here in the Community to assist. Take care.

@john.kubiak 

RE: QB put an unknown person's banking info on our invoice. Went out to customer who deposited to that bank and not ours. We are out $4200!

Do you really think your data is safe with QuickBooks Online?