Hi there,
Making sure the correct amounts are reflecting on your T4s is good way of preventing discrepancies. I'll be happy to point you towards the right direction so you can get this addressed.
To accomplish this you'll need to contact our support team using this link here. One of our specialized payroll agents will be happy to take a look at your T4 and help make the appropriate adjustments.
In the meantime, check out this helpful resource regarding T4s in QB Online: How to prepare T4 slips and summary. Don't hesitate to ask questions in the comments below.