I accidentally put 2009 instead of 2010 for this invoice date, can I change it? The invoice has been posted

After it has been posted, there is no way in VISCO to change it. As a courtesy, the VISCO support team can change it in the DB. You will need to change it manually in your accounting system. In the VISCO System Tables, there is an option called Accounting Allowed dates. We recommend you modify the date to only allow for 2010