Final answer:
To overwrite all existing backup sets, use the WITH INIT option during the backup process. This option clears any previous backups on the media, so it must be used with caution. Other options like WITH FORMAT, WITH EXPIREDATE, and WITH CHECKSUM serve different purposes in the backup procedure.
Step-by-step explanation:
When you want to overwrite all existing backup sets during a backup process, you should use the WITH INIT option. This option tells the backup software to initialize the backup media, effectively overwriting any existing backups with the new data. It's crucial to use this option carefully, as it will remove any previous backups on the media.
On the other hand, the WITH FORMAT option may also be used to format the backup media, but it is generally used when you are dealing with a new media or when you want to change the media's configuration. WITH EXPIREDATE is employed to set a date after which the backup set can be overwritten, and WITH CHECKSUM is used to verify the data during the backup process for any corruption.