Hello Kaiwen Chen,
It is suggested that you keep the Flight Control System as it is and modify the Image Processing and the Path Planning subsystems for the competition. You could change the parameters, but it is not expected that you modify those parameters. It maybe a more difficult task to find the right constant values.
For the competition, I would suggest you to work on the same control system.
However, I would be really intersted to know what is the issue that you observe? Does the Minidrone drift/crash? Some detail or maybe screenshots would really help me know the behaviour better.