How can I change the details of a filed GST payment from one bank account to another?

Hi there, 

Since this your first post in the Community, I'd like to give you a warm welcome. I'll be happy to share more info about tax payments in QuickBooks. 

At this time, the option to edit a tax payment isn't possible. You'll need to delete the payment.

Here are the steps on how to delete tax payment in QuickBooks Online:

1.     Go to the Taxes tab.
2.     Under Sales Tax and choose Payments.
3.     Click the drop-down arrow beside view, then click Delete.
4.     Select Yes on the confirmation screen.    

After following the steps above, you'll have to re-enter the payment with the correct details. To do this, follow steps 1 and 2 above and the 3rd would be clicking the Record Instalment button and entering the appropriate details. Give this a try and let me know how you make out. I'll be on standby in case you need further assistance.