Hopefully, you’ve backed up the data on your Mac to at least one source besides your Mac. It would be nice if Apple enabled complete macOS backup to iCloud as you can with iOS and iPadOS, but that’s another story.
When you’ve backed up your data, there are steps you can take to make sure it’s safe from prying eyes. Chances are you’re using Apple’s own Time Machine for backup. Here’s how to enable encrypted Mac backups with it:
Go to System Preferences > Time Machine.
Choose “Select Backup Disk” and select the drive you want to use for Time Machine back-ups.
If it’s not already enabled, click the “Encrypt backups” box.
Click “Use Disk.”
° Enter and verify your password.
° Click “Encrypt Drive.”
° Click Use Disk.
To use multiple backup disks
I find it a bit confusing, but you can use multiple backup disks. If you do, you can repeat these steps for each disk.
Time Machine works best if you use your backup disk only for Time Machine backups. If you keep files on your backup disk, Time Machine won’t back up those files, and the space available for Time Machine backups is reduced.
Also, as Apple notes in a support document, you may want to set up Time Machine in the evening so that the initial backup can be done overnight. If you back up to a Time Capsule or AirPort Extreme (802.11ac), the initial backup may be faster if your Mac is in the same room as the Time Capsule or AirPort Extreme (802.11ac), or if you connect your Mac to one of the Ethernet ports on the Time Capsule or AirPort Extreme (802.11ac). Subsequent backups take less time.