Your English seemed perfectly clear to me, for what it's worth. We just have a tendency to read things in a negative tone for some reason - one of those human bugs :).
I don't think this is helpful if somebody is trying to learn English subtleties. Responding to a person's thought with "You don't understand", and that's it, implies hostility/rudeness.
People tend to read certain things with a negative tone because people tend to write certain things with a negative tone. That kind of pattern recognition is fundamental to language, not a regrettable quirk. Otherwise "You have absolutely no idea what you're talking about" would be equivalent to "I think you might have misunderstood".
I don't think this is helpful if somebody is trying to learn English subtleties. Responding to a person's thought with "You don't understand", and that's it, implies hostility/rudeness.
People tend to read certain things with a negative tone because people tend to write certain things with a negative tone. That kind of pattern recognition is fundamental to language, not a regrettable quirk. Otherwise "You have absolutely no idea what you're talking about" would be equivalent to "I think you might have misunderstood".