I want to know the best subjects that can make a good master in architecture and the problems which can be solved in architecture (in masters) all over the world.
Subjects for master degree in architecture
To a great extent, one's interest and aptitude are guiding factors in making the best out of any study, academic or otherwise. It is generally helpful, at the masters level, that the student develops existing skills and interests rather than trying to develop entirely new ones.
As for courses, perhaps it is the way the course is taught that is more important. Any masters course should aim to develop the students' ability to think critically about any given situation or problem in order to come up with unbiased answers. I feel this applies to research, policy making, as well as design.