It seems that you cannot change the financial year until the current one is over. The financial year can last between 3 to 18 months. This is set when you first enter the details for a company. If the financial year is no closed, you can do whatever modifications do you want to the data, but not to the year. To make modifications, you need to go under Activities > Enter Documents. For additional information, check the documentation of the product from the following website.
