When you show a percussion kit using the grid or five-line staff presentation type, it’s not always clear which dynamics apply to which instruments, since you could very well write different dynamics for every instrument in the kit at the same point. So the set of dynamics you see when you use the kit and grid is different than the set of dynamics you see when using the single-line instruments presentation type. The dynamics that appear when you use the grid or five-line staff presentation type have to be entered on the grid or five-line staff.