Press Down the indicated number of times to change each of the four medals.

Invisibility:
Medal 1 - 6 times
Medal 2 - 0 times
Medal 3 - 4 times
Medal 4 - 2 times

Level skip:
Pause, then press Select to skip the level
Medal 1 - 4 times
Medal 2 - 2 times
Medal 3 - 0 times
Medal 4 - 3 times

Unlimited Time:
Medal 1 - 7 times
Medal 2 - 4 times
Medal 3 - 1 time
Medal 4 - 6 times