An alternative login keyboard
Finally, you will notice layouts are applied on a per-account basis. That has its conveniences, but it also has the side-effect that the default system keyboard layout will be used at the login window when no account-specific settings are active.
If you don't want to always use the default layout at login, you can enable the same input menu at the login window. To do so, go to the Users & Groups preference pane, open Login Options (under the list of user accounts), then select the option to Show Input Menu In Login Window. (You'll need to unlock this preference pane first.)
This done, you can then access the input menu to change your keyboard layout when logging in. However, if you find that you're always accessing this menu at the login window, you might consider changing the default keyboard layout itself. Unfortunately there is no specific setting for doing this; there is, however, an easy workaround.
First, configure your user account to use the desired keyboard layout (as instructed above). Then in the Finder, hold the Option key down and choose Library from the Go menu. When the library window opens, go to the Preferences folder and locate the file com.apple.HIToolbox.plist. Select it and press Command-C to copy it.
Next, go to the Finder and navigate to the Macintosh HD > Library > Preferences folder. Locate the same file in this directory and rename it to something like com.apple.HIToolboix.plist-old to make it a backup. Then press Command-V to paste the copied file in this location.
After doing this, you will need to ensure the file is properly readable by the system, so open the Terminal and run the following two commands (you can copy both and paste them together at the Terminal command line:
sudo chown root:wheel /Library/Preferences/com.apple.HIToolbox.plist; sudo chmod 644 /Library/Preferences/com.apple.HIToolbox.plist
With these commands entered, restart your system. The keyboard layout preferences you set for your account will now be applied to the login window. If you would like to revert this setting, you can do so by deleting the copied file and then renaming the backup file you saved, removing the -old you appended to its name. Again, follow this by restarting your Mac.
While this may seem like a round-about way of doing things, it can be useful for a couple of reasons. First, if you primarily use an alternative keyboard layout like Dvorak or Colemak, then you can set this up to be used seamlessly between your login window and your account.
Additionally, you can use the alternative keyboard layout as an extra layer of security: If someone figures our your password and tries to log into your account, by simply having a non-standard keyboard layout like Dvorak configured for the login window will foil the miscreant. Granted, that'll also mean you have to know the Dvorak layout to log in yourself. But it can be another way to thwart unwanted entry into your Mac account.
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