You're certainly welcome, @Zseb.
I realize that going through years of transactions can be a daunting task, especially if you have limited time. One option that you may wish to consider is working on reconciling the accounts. This would help to identify some of the root causes of the discrepancies.
Should you decide that you want to follow that path, I recommend the following resource as it contains numerous articles to help troubleshoot the process: Reconcile Hub.
Alternatively, there is the option of making journal entries to help balance the accounts. However, you may wish to consider reaching out to your accountant to ensure that the correct accounts are chosen.
Please know that the Community is here and I'm happy to answer any additional questions that you may have. Cheering you to continued success.