If you are reading this, it is because you have been contacted by your tenant or you have are looking at the tenant's page and the wrong rent amount is showing due.
Click on Tenants
Click Edit on the respective tenant
Click on Invoices
Click View on the invoice
As long as there are no payments applied to the invoice, then you can click Add Charge (This action is to create a charge that will replace the old charge line e.g. for Rent you add a new rent charge and delete the old. etc..) Provide the description and the amount
Click Save > Delete old or incorrect charges and you are done.