Photos in your System Photo Library are available in apps like iMovie, Pages, and Keynote. You can also sync them to iOS devices and view them on Apple TV. And if you want to use your own images as your desktop picture or screen saver, the images need to be in your System Photo Library before you can select them in System Preferences.
If you have only one photo library, then it's the System Photo Library. Otherwise, the first photo library that you create or open in Photos will become the System Photo Library. If you have more than one library, you might need to designate a System Photo Library, so other apps can access the photos and videos you want them to use.
Jan 31, 2017 Over the years Apple has made steady improvements to how our devices sync content. Feature Request: iCloud Photo Library support for multiple Apple IDs. While iCloud Photo Sharing. Nov 23, 2016 Moving a Mac’s Photos Library. Apple’s Photos app lets you create multiple photo libraries. To point the program to the library’s new location, hold down the Mac’s Option key. Dec 23, 2015 Sync Sharepoint site documents library on Mac Is there a way I could sync sharepoint (on office 365) documents library with Mac running El Capitan. With the OneDrive for Business sync client for Mac, we can sync our files from the OneDrive for Business library to a Mac. To sync a SharePoint Document Library is currently not supported.
Follow these steps to designate a System Photo Library:
If you open a second or different library in the Photos app, and you haven't designated it as the System Photo Library, other applications will use photos from the original System Photo Library. Hold down the Option key when you open Photos to see which library is set as the System Photo Library.
You can use iCloud Photos, Shared Albums, and My Photo Stream only with the System Photo Library. If you choose a different library in Photos without designating it as the System Photo Library, the iCloud tab in Photos preferences is disabled:
If you designate a new library as the System Photo Library and then turn on iCloud Photos, the photos and videos in the new library will merge with those already in your iCloud Photos. If you want to keep the contents of your photo libraries separate, don’t turn on iCloud Photos for more than one library in Photos.