How do I add a transaction that was made to an old invoice that was paid into an old bank account which is now closed and before i started using Quickbooks?

Welcome to the Community forum, jandmtravel.

You can manually create a bank account so you'd still able to track transactions deposited into that account. 

Here's how:

1. In the left menu, click Accounting. 
2. Go to the Chart of Accounts tab. 
3. Hit the New button at the upper right hand. 
4. In the Account window, pick Bank for the Account Type, then choose the correct Detail Type. 
5. Enter the name of the bank in the Name box and other necessary information.
6. Click Save and Close. 

Once done, you can now create an invoice and receive payment deposited to the bank account created.

As always, feel free to visit our QuickBooks Community help website if you need tips and related articles in the future.

You're always welcome to post again if you have any other concerns. Wishing you and your business continued success.