Back up using a new external drive
can someone please explain how to back up my mackbook air to a new external portable SSD
samsung drive T7?
Back up your Mac with Time Machine - Apple Support
1) Use Disk Utility to format the new drive. GUID partition scheme and APFS format. Name it whatever you like.
2) If Time Machine prompts you with a question asking if you want to use this new drive as a backup destination, click the affirmative.