I'll try to post on better threads. Yes, sometimes I post on the mega threads that I am interested in the topics discussed by the members. For example the thread about football matches, I am interested to join the discussion about the current matches. It is because I am a football enthusiast (football lover). But sometimes I post on a new thread as well.
You are free to post anywhere or on any thread as long as you understand the topic, but if you want to improve then you may need a change in your posting habits. Try to avoid a lot of mega threads, it will make you feel better I think.
I see you are also active in the local board, so the local community I think is also good for improvement. The problem is that you have to try to do better and really improve in terms of post quality if you want to move up the rankings. But congratulations to you, nurilham.