Welcome to QuickBooks Online! wallace. I'm here to ensure you can apply the payment to the invoice created in QuickBooks Self-Employed (QBSE) to QuickBooks Online (QBO). 

When we transfer our data from QBSE to QBO, the invoices become unpaid, as payments cannot be moved.   

To apply the payment to the invoice created in QBSE, we have to create a Bank deposit affecting Account Receivable (AR) and link it as payment to the invoice through the Receive payment option. 

Here's how: 

1. Go to + New.
2. Choose Bank Deposit.
3. From the Account dropdown menu, select the account you want to put the money into.
4. Select the checkbox for each transaction you want to combine.
5. Make sure the total of the chosen transactions matches your deposit slip. Use your deposit slip as a reference.
6. Hit Save and close.

Then, we can link it to the invoice. 

Perform the steps below: 

1. Locate the +New button. 
2. Under the Customer column, select the Receive payment. 
3. Select the specific customer. 
4. Enter the necessary information. 
5. Click Save and close.   

Afterward, we can match the deposit from the bank feeds page to the one created within the program. 

Additionally, you can visit this article about managing your newly created QBO account: Get started and adjust settings after you sign up for QuickBooks Online. 

Please don't hesitate to comment on this post if you have more queries regarding QBO. I'll be here to assist. Stay safe!