Enter the following at the password screen.

Level 2: cfr
Level 3: hof
Level 4: rcl
Level 5: slr
Level 6: jho
Level 7: fcj
Level 8: crs
Level 9: ljs
Level 10: roc
Level 11: osh
Level 12: hrl
Level 13: fsl
Level 14: ofj
Level 15: jrf
Level 16: lol
Level 17: flr
Level 18: rhj

At the title screen hold A, B & C until you reach a place called "parents option". There you will find options like level select and much more.