I have posted to another board indeed but after listening to the opinions, i decided to eradicate my bad habit of fixing the arms.
I tried to adopt the so-called full-arm playing approach.
It turned out that my fingers are getting much relaxed and seems I can control the dynamic much better.
Feel free to leave me a comment

I used a iphone to record it.
My piano has some problem with the pedal....so you can hear some strange sound...
