Hi Shezz24,

If there are no super payments made from the pay run, you can unlock and refinalise the pay run to make changes. And then, submit an updated pay event to update the YTD to the ATO. 

Here's how to unlock the pay run:

1. Click on the Employees tab.
2. Click on Pay Runs.
3. Locate the pay run and open it, and click on Pay Run Actions.
4. Click on Unlock.
5. Enter a reason to unlock the pay run, and click OK.

Once done, make the changes on the pay run and finalise it once again. Then, you need to create and lodge an updated pay event. 

1. Click on the Employees tab.
2. Click on Report tab.
3. Click on Single Touch Payroll.
4. Click on Create Update Event button.
5. Select the Financial Year and Pay schedule, click Create.

If you have more questions with QuickBooks Online please let me know in your reply. I'll be here to help you. Have nice day!