A smart TV will have different apps available depending on what market it is sold in. TVS sold outside North America are often unable to switch region to the USA. Some apps are locked down to serial numbers of the TV model and as this limitation is based on hardware it can't be unlocked.

That said - changing the region to one of the following should provide access to the most popular apps on most TVS: USA, Mexico, Brazil, Canada, UK, Finland, Norway, Sweden and Denmark.