Hi JANELLE
With the original pay (incorrect amount) still sitting in the Prepare Electronic Payments window, it means it hasn't been recorded as an electronic payment which updates the bank account balance yet. So you need to tick this payment, select the bank account to pay from, click on 'Bank file' to record the electronic payment, there is no need to save the .ABA file.
On the other hand, if you reversed the incorrect pay, it will automatically prompt to change the payment method from electronic to Cash, thus skipping the 'Prepare Electronic Payment' step and post to the bank account directly. Once the original pay is also processed as an electronic payment, there should be a withdrawal as well as a deposit in your bank register to cancel each other out.
I hope this helps. Please feel free to reach out if you have more questions.