When you're logged in, click on your account, then click 'Nominated Account' in the menu on the left.
You'll be able to see the details of the account you selected to pay in from and/or make payments to.
To change your Nominated Account, select 'My details' in the menu on the left and then 'External Accounts'. You can choose a different Nominated Account from the 'External Accounts' list by clicking it.
If the account you want to use as your Nominated Account doesn't appear in the 'External Accounts' list, you'll need to add it.
To do that, select 'My details' in the menu on the left and then 'External Accounts'. Add the details and then return to 'Nominated Accounts'.
If your account is a bond that will mature within the next 14 days, you won't be able to change the details of your Nominated Account.