First step is to figure out what the balances in Accounts Receivable, Accounts Payable, and Payroll should be.

I suggest printing a Vendor Detail report - 'zero days' and a Customer Detail report - 'zero days'.  These will show what remains outstanding for each supplier/customer according to the respective module.  Compare this to 'real life' for each customer and note the differences.

It's a bit harder to get a really good list of outstanding balances according to the payroll system.  You can print the Payroll Summary report for the current year, which will give you a one page report per employee.  Or, you can preview the Payroll Summary report on screen and then open it in Excel, which will give you one huge Excel file with a row for each employee.  Whichever format you use, look it over to figure out what the correct balances for (a) loans/advances outstanding and (b) vacation pay banked are for each employee.

Once you know what the correct balances are, the next step is to make the required changes.  This is trickier, especially if the bad entries go back over a period of years.