Can ex-employees change their earnings?

Thanks for sharing your concern with us here in the Community, @lsps2010.

Let me shed some light about modifying paychecks in QuickBooks Online.

When a paycheck has been processed, and taxes were paid, you'll need to reach out to our Customer Care Team. They have the tools that can check on your transactions and make necessary corrections.

If the paycheck was not submitted yet, a user can still edit the earnings. I'm sharing here some links that provide information on when you can modify or delete a paycheck in QuickBooks Online:

• Learn how to change an employee paycheck in Online Payroll
• Edit a payroll paycheck

To prevent this issue from happening, you'll need to make sure to deactivate the ex-employee from the list of your users. This way, he can no longer access your account and generate changes.

To deactivate a user:

1. Sign in to QuickBooks with a user profile that has permission to manage users.
2. Select Gear icon.
3. Select Manage users.
4. Find the user you want to delete. Then select the arrow icon in the Action column.
5. Select Delete.
6. In the confirmation window, select Delete again.

You can refer to this article for more details about managing your user access in QBO: Learn how to add, manage, or delete user profiles.

I'd also encourage you to run the YTD report of your employee to ensure the accuracy of his payroll details. 

To do that:

1. Go to Reports.
2. Find the Payroll Details report on the search field.
3. Filter your report by employee, date range, and work location, and then select Run report.

Lastly, for more details about the payroll reports that you can pull up in QBO, kindly see this link: Learn how to run payroll reports.

Stay in touch if there's anything else you need while working with QuickBooks. I'll be around for you. Take care!