What version of FN are you using? 7.5? 8.0?We have expanded the Chart of Accounts and you need to update each data file to the new Chart of Accounts. Please make sure you read the instructions carefully, as the update involves changing category names. I recommend that you print out your current Chart of Accounts for a reference.
See the post Updating the Chart of Accounts for instructions.
This is the only expansion of groups and categories that has been done for the FN Chart of Accounts. If this does not resolve your issue, you might want to consider reorganizing your accounts. You can change a category to cover multiple areas (e.g., Office Expenses can include utilities, IT fees, equipment repair fees, etc. instead of having a separate category for each type of office expense.) Then you can move accounts into the new category and use the now available category for what you need.
Please respond to this post with any further questions.