These are instructions on how to change the location of your iPhone, iPad, and iPod touch backups. You may want to do this if your iOS device backups are taking up too much space on your primary hard drive.
If you're familiar with Terminal you can find a more advanced version of this tutorial here.
Step One Open Finder from your Dock.
Select Go to Folder from the Go menu.
Type ~/Library/Application Support/MobileSync into the entryfield and click Go.
Step Two Here you'll find the Backup folder that macOS uses for your iOS devices. Click the folder's name twice and rename it to Backup (Old). Alternatively, you could copy or move the folder to a new location; however, you'll need to be careful with this folder as it contains all your previous backups.
Step Three Open a new Finder window (Command + N). Navigate to the location you'd like your backups saved and create a new folder named Backup. You can do this by selecting New Folder from the File menu.
In our example, we created a new folder named Backup on an external drive.
Step Four Launch Terminal from the Applications > Utilities folder.
Step Five Type the following command into the Terminal window, replacing /Volumes/Untitled/Backup with the location of your new Backup folder.
If you're using macOS Mojave, you will first need to change the permissions for Terminal on your Mac. To do so:
1-Open System Preference.
2- Select Security & Privacy.
3- Choose the Privacy tab.
4- If this screen is locked, select Click the lock to make changes at the bottom left of the screen. Otherwise, skip to Step 7.
5 - Enter your system password and click Unlock on the popup screen.
6-Click Full Disk Access on the left-hand side of the screen.
7-Choose + to add Terminal to the list of apps with full control on your computer.
8-In the Finder screen that's displayed, type Terminal in the search box.
9- In the search results, highlight Terminal.
10- Tap Open.