Overwrite protection period & Apend period

I am new to Backup Exec. Need some help here.

Daily tape (Mon-Thurs)

8 tapes

Retention period = 2 weeks

Current settings OPP = 12 days, AP = Infinite allow append

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How can I configure the OPP and AP? I don't need to append data to the tape, as we have sufficient tape for daily backup.

Current settings doesn't seems to remove expired data (after 12 days OPP) automatically, which I wish it can.

Please help. Thanks.