Hi @Sheldon P,
Welcome to the Microsoft Q&A Platform! Thank you for asking your question here.
Once you create a disk encryption set with a particular encryption type, it cannot be changed. If you want to use a different encryption type, you must create a new disk encryption set.
Please visit this link Set up your disk encryption set-https://learn.microsoft.com/en-us/azure/virtual-machines/disks-enable-customer-managed-keys-portal#set-up-your-disk-encryption-set
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