Which settings in System Preferences are global for all users? Some things in System Preferences obviously apply to only one user:


Desktop Picture
Appearance accent colour and highlight colour
Dock size


While others obviously apply to all users:


Startup Disk
FileVault full disk encryption
Show fast user switching menu


For people who are not very experienced with macOS (and even some experienced users!) is there any way to tell whether a given setting will apply to all users or just the current user, other than constantly tweaking settings and switching between user accounts? Is there a reference somewhere?

I'm motivated to understand this better because I often find myself setting up new Macs for people, and I find myself wondering which settings are useful to apply in System Preferences while not logged in as the eventual end user.
One simple (but not 100% reliable) way to tell is to log in as a "standard" user (non-administrator), and see what settings you can change without first clicking a padlock and authenticating as an admin. Very few system-wide settings can be changed by standard users, so if you can change it this way, it's almost certainly per-user.

You can run essentially the same test as an admin by going to the Security &amp; Privacy preferences, clicking the padlock &amp; authenticating, clicking the "Advanced" button, and selecting "Require an administrator password to access system-wide preferences". Then dismiss the Advanced dialog, and click the padlock again to re-lock the system-wide settings.

There are a few exceptions and special cases. Switching between network "locations", for instance: locations are system-wide, and it takes admin rights to create/modify them, but once they're defined standard users can switch between them.

Joining a Wi-Fi network is similar. Any user can join a network, check the "Remember this network" checkbox, and it'll be added to the system-wide Preferred Networks list (and its password will be copied into the System keychain, so the Mac can connect no matter who's logged in). Well, unless the Wi-Fi network uses "Enterprise" (802.1X) authentication; in that case, you're authenticating to the network as a particular user (rather than with a general shared password), so macOS assumes it should be per-user on the Mac as well.

Note that it's normal for a single preference pane to have a mix of system-wide and per-user settings. Go into the Security &amp; Privacy preference pane, and under the General tab it'll have the controls to change your password and require your password after sleeping / screen saver available, and all the others dimmed. Those are per-user, the dimmed ones are system-wide policies.

An even more extreme example of this is iCloud. Most iCloud services are per-user (i.e. each user on the Mac connects to their iCloud account and uses its data/services), but Find My Mac is a computer-wide feature (it's tracking the Mac, not a particular user on it), and can only be turned on for one user's iCloud account at a time.

Oh, and I should mention software installation: any user can install apps via Apple's App Store, but once installed they're available system-wide. For non-App-Store software, it depends on the specific program, but generally it'll either require admin rights to install or be per-user only (e.g. it might create a personal Applications folder under the user's home and install there instead of the regular system-wide Applications folder).