To set/reset an Employee’s PIN, choose Manage > Employees > List
Click the Reset PIN icon against the Employee’s name
Enter the new PIN number
Confirm the new PIN number
The pin number must be unique within this account and contain only numerical digits. Ovatu suggests using a 4 digit PIN
Click Change to change the PIN or Close to cancel
You can also set the app to timeout, so that the PIN is required to be entered before it can be used again. See How do I customise my security settings?