For macOS Tahoe
Intro
Ever since the introduction of macOS 15, you have been stuck with using your region's default voice as the voice at the login window (Samantha for English US, Daniel for English UK, etc.).
Previously, you could just change this back to whatever voice you like. With the introduction of macOS 15, this became impossible because you couldn't add voices to the voice rotor on the login screen. Pressing VO+F8 doesn't work to open VoiceOver Utility.
Then there's no way to do this. Why even bother writing this guide?
That's what I thought up until a few months ago. There is a way to get all of your custom VoiceOver preferences to be used on the login screen, beyond the voice, such as verbosity settings, Braille settings, and anything else you have modified for your user account.
VoiceOver's settings for the login window are the same as the root user’s. To change these settings, you will need to log in as the root user.
You can either manually configure VO settings for the login window while logged into the root user, or import your preferences from your current user account into the root account. That is the method I will be covering here.
About the root user
If you've used a Unix-based system like Linux, you may be familiar with the root user (commonly called the admin account on Windows). The root user, also known as the super user, has all the power to do whatever it likes, from deleting system files to running admin commands, to wiping out your entire drive. The sole exception to this are files, like those in the System folder (/system), that are protected by System Integrity Protection (SIP), enabled by default on all installations of macOS since version 10.11.
Just by logging into the root user, you won't cause any damage to your system. Just be careful if you do need to delete any system files. Most users shouldn't need to delete files related to the system.
Exporting your preferences
In VoiceOver Utility, you can export your preferences by pressing Command+Shift+E.
Save them to a location you have access to, such as your desktop or a flash drive.
Enabling/Disabling the root user
- Open Directory Utility either from Spotlight or
/System/Library/CoreServices/Applications/Directory Utility.app. - Press the button that says "Click the lock to make changes".
- Use TouchID or enter your password to unlock.
- In the edit menu, select the option to enable the root user.
- You will then be asked to enter a password for the root user. Be sure to make it different than your normal password. Remember that the root user has full read/write access to every file on the system not protected by SIP (see above section for more details).
- Once you are done modifying VO settings, make sure to come back here and disable the root user.
Logging into the root user
- Log out of your current user either through the menu bar or
Command+Shift+Q. - On the login screen, press Option+Enter to be able to enter the name and password for a user.
- In the user name field, enter
root. That's, r, o, o, t, in all lowercase. - In the password field, type the password you set in Directory Utility.
- Press enter, log in, and complete any setup assistant screens until you are at the desktop; no need to log into an Apple Account.
Changing VO Settings
Now for the fun part. You'd think you can press VO+F8, right? Nope! For whatever reason, some commands like opening VO utility as well as things like the application/window chooser menus don't work here.
VoiceOver Utility can be found at /System/Applications/Utilities/VoiceOver Utility.app. Once in VoiceOver Utility, import your preferences with Command+Shift+I.
If certain folders say "No permission to read", copy the preferences file with this terminal command while logged into the root user: (be sure to replace /path/to/Preferences.voprefs with the actual path to the preferences file)
mkdir -p "$HOME/Desktop" && cp "/path/to/Preferences.voprefs" "$HOME/Desktop/VoiceOverArchive.voprefs"
If for whatever reason it won't open, run this:
open -a "/System/Applications/Utilities/VoiceOver Utility.app" "$HOME/Desktop/VoiceOver Archive.voprefs"
Terminal can be found at /System/Applications/Utilities/Terminal.app, or via Spotlight.
If that works, import your preferences file like normal.
Once you've imported your preferences and they work on the root user, you can log out and back into your current user.
Note: The root user is still enabled unless you manually disable it. Due to the power that this user account has if in the wrong hands, it is generally recommended to disable it once you've made your changes.
Troubleshooting
FileVault is on, and when I start up my Mac, my settings don't take effect.
If only FileVault could use these settings. Since, when enabled, it must decrypt your disk before macOS can boot, any custom settings, including those of the root user, are not yet loaded at the login window. As of now, there is no way I know of to modify the settings in the FileVault/Recovery environment beyond changing rate/volume/pitch.
VoiceOver Utility stops responding
Sometimes this happens. If VoiceOver works as you expect with your settings, you are free to shut down the Mac and restart it.
Conclusion
With these steps, you can have your custom settings work on the login window, and if you so desire, get rid of Samantha/your region's default voice once and for all!