Hi Raniac,
Great job catching the change in expenses and working towards fixing it. QuickBooks Online makes it easy for you to enter and track your expenses so you can find where to start. I can help point you in the right direction.
When you are looking at how to adjust accounts and how to make changes from previous years balances it is best that you reach out to your accountant. This is due to an accountant being trained on how to make these changes and adjust accounts. If you don't currently have an accountant we can help with that by going to our find an accountant page to find one in your area to help.
Once you talk to your accountant and they tell you what needs to be done we can assist on how to enter it.
Hope this helps get you back on track!