If the cheques were posted as Manual Checks with a Cash Invoice, there is an option in the company profile that allows to reverse the cash invoices at the same time than the cheques.
In the System Options tab, change the Reverse cash invoice with check to Always and it will reverse the cash invoices with the cheques always. If you don't want to enable it to always, will need to right click and select Reconcile in each cheque and select the option to reverse the cash invoice.
If the cheques were printed in a check run or as payments in Manual Checks, you will need to reverse the checks and then adjust the invoices individually.
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Patricia Balbuena Cotlear
AP SMART SUPPORT
236 991 3060