What's wrong with that is that I want to speak English in a dormitory for the mentally handicapped

Although I live in Finland, I was born here and lived here all my life, I can speak English perfectly. I would always like to speak only English. However, I am told that in some situations I have to speak Finnish and it annoys me. No other resident in the dormit speaks any English and that is why I have to speak Finnish to them so that they understand me. It annoys me. Why can't they speak English?

The nurses also say that they prefer to speak Finnish to me rather than English, even though they know English.

Sometimes I’m angry and bark at other residents in English because they annoy me and then they don’t understand what I’m saying because they don’t know English, but then the instructors say it’s wrong for other residents. Why is it wrong? Why can’t I bark at them in a language they don’t understand when they don’t suffer from it?