Backup Exec Append and Overwrite settings to keep 4 weeks of data on tape.

Hello,

Running Backup Exec 2010 R2, we have 1 tape for each day of the week and run the backup daily.  The backup isn't very big so we can fit at the very minimum 4 backups on each tape.  Originally we had the media set to Infinite - Allow Append.  Of course eventually the tapes were full and the backup would have to fnish on the next days tape.  How could we set the overwrite protection and append period to allow for 4 backups to be kept on each tape before overwriting the tape fully?

Thanks