Backup exec 2012 conf issues

Hi,

    I have downloaded Symantec Backup Exec 2012 and installed it in Windows 2008 Server Standard Edition. I have an IBM Tape drive attached to it and need to configure backup for six days starting on Mon,Tue..Sat in 5 tape cartridges(Friday & Saturday ll run in the same cartridge). I configured to check the backup(sample run on the tapes), Now when i try to erase the cartridge, re-label and re-configure it, the data is not erased, also when i schedule the job it fails since I have set overwrite protection period and append period for the media. Now i want to append and overwtire on these medias and remove the previous set up. how to do this, any inputs will be highly appreciated.

regards

geeks