Good morning

I'm very new to this, so please bear with me! 

We invoice based on 30 days from end of month.  I have changed the settings (record and transactions settings) to End of new month (net monthly), but when I run the aged debtors report/ breakdown nothing has changed and just states the due date (30 days from invoice).  

How can I change this or see on the account which is overdue or current?

Thanks very much!