If your SM3 Slim Mechanical Keyboard (ST-BTSMKW3) types different characters than expected, the issue is usually caused by your operating system's keyboard layout or language settings.

Try these steps:

1. On macOS, go to System Settings > Keyboard > Input Sources and make sure the correct keyboard layout (such as U.S.) is selected.
2. Verify that Caps Lock or Num Lock is not enabled unintentionally.
3. Test the keyboard in a plain text editor to determine whether the issue is specific to one application.
4. Remove and then re-add the keyboard input source in your operating system's keyboard settings.

If the incorrect key mappings persist across multiple devices and operating systems, please contact Customer Support for warranty assistance.