Norton 360 Backup Settings---Append instead of FULL Backup?

Can anyone assist me in the setup of the Backup feature in Norton 360 Version 21.6.0.32? It appears every time a full hard drive backup runs, it copies all the files, all the time. It piles on the data each backup, instead of just appending the files that had changes. Is there any way of setting the program to append and not copy the hard drive completely each time it runs????

Please help!

Thanks,

LesG