Transactions are matched incorrectly. Several clients are invoiced for the same amount. Incorrect invoices are being marked as paid and matched to another client payment.

I've got the steps to correct your invoices, khadija. 

If this is from the Banking section, it may be possible you have created a bank rules. In that matter, I suggest making it inactive. 

Here's how: 

1. Go to Transactions and choose the Rules tab. 
2. Select the rule, click the dropdown menu, and hit Disable. 
   

Afterward, we can undo the transactions from the Categorised tab, and start manually finding a match.  

Additionally, I've included this article about personalizing and adding specific info to your sales forms: Customise invoices, estimates, and sales receipts in QuickBooks Online. 

Let me know if you have more questions about managing your transactions. I'll be here to assist.