Changing keyboard language on ATV3

Hi,

I'm living in Belgium (under a bad weather....) and I've recently bought an ATV3 for my wife, so she is now able to watch her favourite series on TV screen instead of watching them on a small mini Ipad screen.... which is very tyring for her eyes
last year during our trip in Thailand we also bought a thai/eng wireless keyboard (Apple) and we'd like to use it with the ATV3 so she'll be able to search movie from Youtube and watch them in full screen which is not the cas when watching them when connecting the Mini Ipad to the ATV3

so my question is

does anybody know ho to change the keyboard language in the ATV3 settings, so she'll be able to make her own research by by using Thai characters ?

thanks in advance

Guy