I do not know what to say to you, I understand. You stay there and I am here. Each person is not well understood. And my English is not good, you do not understand.
I don't know how to say, do you understand me. You are at it, and I live here. Person does not understand my English, and not good at all, you don't understand.
I don't know what to say to you is that you understand me, and I am here. Different people do not understand, and my English is not very good, is it? I do, you don't understand