To troubleshoot your Smart TV not displaying subtitles on certain programs:

1. Identify which programs are not displaying subtitles
2. Check whether subtitles are available for the program
3. Check the settings of the TV and network connection
4. Update the firmware of the TV, if necessary
5. Adjust the subtitle settings on the device
6. Reset the codepage of the device
7. Check external devices connected to the TV
8. Contact the TV manufacturer for further assistance