Thanks for adding a clarification and sharing screenshot, @ Kirill Brusov.
Allow me to add some details on how you can fix the payment/deposit.
Based on the screenshot, for you to follow the second step provided by the previous representative, you need to click on the invoice link under the Outstanding Transactions. Once you're on the invoice page you'll see the blue text located in the upper right hand below Paid,
To learn more about QuickBooks payment, check out this article: Find out when QuickBooks Payments deposits customer payments.
Moreover, I've included this reference that you can use in the future when you're ready to assess your business' profits: Categorize and match online bank transactions in QuickBooks Online. You can also review the articles here for the next steps, such as reconciliation or undoing reconciliation.
Our doors are always open to help you again if you need further assistance sending invoice reminders. Have a great day.