Here's how you can enable encryption for your Time Machine backups in OS X. For new Time Machine backups: 1. Connect the backup drive to your Mac. 2. Click the checkbox for "Encrypt Backups." For existing Time Machine backups: 1. Go to System Preferences. 2. Go to Time Machine. 3. Go to Options. 4. Select your Time Machine backup drive. 5. Select "Encrypt Backup Disk" or "Encrypt Backups."
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Encrypt Time Machine Backups with OS X | OS X Daily