We earlier coded the matrix called `create_right_button_matrix`, which creates a two-dimensional matrix with the number of rows equal to `MAX_NUMBER_OF_DRUM_SAMPLES`. The number of columns would be decided by multiplying the number of units by the beats per unit values selected by the end user. Its formula can be given as follows:

*Number of columns of buttons = Number of units x BPU*

This means that every time the user changes the number of units or the beats per unit, the button matrix should be redrawn to change the number of columns. This change should also be reflected in our underlying data structure. ...