There are a few different steps to investigate why your Smart TV is not displaying the correct time zone:

1. Check if the Smart TV is connected to the internet by checking your network settings.
2. If the TV is connected, try resetting the time zone settings in the TV menu.
3. Re-attempt to manually set the time zone if the reset does not work.
4. If the time zone settings still do not update try performing a factory reset.
5. If the time zone is still not correct try contacting the TV manufacturer for further assistance.