Norton 360 Backup

I have Norton 360 (not sure which version; 2011 or 2012, I think).  The backup feature quickly fills up the external hard drive I use to store the backup files.  I have about 350 GB of files to backup, but the backup file is close to 1 TB.  Does 360 overwrite old back files, or simply create new ones?   I have had this problem before; I was directed into a menu that would allow me to change settings and delete files backed up that I didn't want to keep through Norton 360.  The problem I ran into was that this would take about 2 months to complete.  The setup process itself seems to take about an hour.  I ended up simply deleting the backup files from the external drive altogether, which took just a few minutes.  I have read messages on this forum about dealing with this problem, and it seems to have a lot of hoops to jump through. 

 

I also use the Carbonite online service, and am not sure I need the 360 backup. How do I disable it?