bad debt

@Eve2019 

You really can't make the old invoice unpaid at this point.  The revenue from the old invoice was offset with a bad debt expense entry so there was no income.  I would copy the old invoice dated in the current period and receive payment on that.    

I agree with Rainflurry's advice on reversing bad debt records in QuickBooks Desktop (QBDT), @Eve2019. Let me provide you with the step-by-step process to get this on record.

First off, we can copy the same invoice by following the guidelines below. Then, we can make alterations to the date to post it on today's period.

1. Go to the Customers menu and select Customer Center.
   
2. Locate your client who made a payment to an invoice.
3. Under the Transactions tab, filter it only shows invoices by clicking the Show dropdown and selecting Invoices.
   
4. Click on the invoice that your client paid to open the transaction.
5. Select the Create a Copy option to duplicate it and alter the Date to today's period.
   

    

After that, let's record the payment using the steps below:

1. Go back to the Customers menu and select Received Payments.
   
2. Select the customer's name in the Received From field.
3. Put a checkmark on the transaction for the amount we're receiving.
4. Click Save & Close.
   

    

Moreover, I’ll add this article to learn more about the principles of reporting data. You can also check on how you can customize them more effectively: Understand reports. 

If you have further inquiries about managing sales transactions, feel free to visit the Community. I wish your business the best of luck in prospering. Please take care and stay safe.

@Eve2019 

One other thought that came to mind: If you have inventory items on the original invoice, QB will pull another item(s) from inventory.  You will need to go back and add those items to inventory using a qty adjustment and assign the adjustment to COGS.  If there were no inventory items on the invoice then you should be able to copy it without any changes.