Preferences window is shown at login

If you manually registered Karabiner-Elements to login items, the preferences window will always appear at startup.

Karabiner-Elements will start automatically via launchd even if it is not in login item, so remove it from your login items.

1. Open System Preferences.
2. Open Users & Groups.
3. Choose your account from the sidebar.
4. Open Login Items tab.
5. Remove Karabiner-Elements from login items.