Change Time Machine preferences on Mac
On your Mac, use Time Machine preferences to select a backup disk, set Time Machine to back up automatically, and specify options, such as excluding files from a backup and being notified when old backups are deleted.
To change these preferences, choose Apple menu 
> System Preferences, then click Time Machine.
Open Time Machine preferences for me
Option | Description |
|---|---|
Back Up Automatically | Select to have Time Machine automatically back up your files. |
Select Backup Disk, Select Disk, Add or Remove Backup Disk | If you haven’t set up Time Machine, click Select Backup Disk to set up a backup disk. Repeat the steps for each backup disk you want to set up. If you already set up Time Machine, your backup disks are listed, and information about each backup disk is shown. To select, add, or remove backup disks, click Select Disk or Add or Remove Backup Disk. |
Options | Set options to exclude items from being backed up and to back up while on battery power. |
Show Time Machine in menu bar | Add a Time Machine menu to the menu bar along the top of your screen. |
Note: If you create a backup on a Mac or partition with macOS Catalina, you can only use that backup on Mac computers or partitions with macOS Catalina.