Go to options and then “cheats.” You now have to strum with the frets to enter the cheat code. Two or more notes in parentheses indicate a chord.
G=Green, R=Red, Y=Yellow, B=Blue, O=Orange

Effect Code
Air Guitar (BY) (GY) (GY) (RB) (RB) (RY) (RY) (BY) (GY) (GY) (RB) (RB) (RY) (RY) (GY) (GY) (RY) (RY)
Easy Expert (does not work in Career mode) (GR) (GY) (YB) (RB) (BO) (YO) (RY) (RB)
Hyperspeed OBOYOBOY
Large Gems G R G Y G B G O G B G Y G R G (GR) (RY) (GR) (YB) (GR) (BO) (GR) (YB) (GR) (RY) (GR) (GY)
No Fail (does not work in career mode) (GR) B (GR) (GY) B (GY) (RY) O (RY) (GY) Y (GY) (GR)
Performance Mode (RY) (RB) (RO) (RB) (RY) (GB) (RY) (RB)
Precision Mode (GR) (GR) (GR) (RY) (RY) (RB) (RB) (YB) (YO) (YO) (GR) (GR) (GR) (RY) (RY) (RB) (RB) (YB) (YO) (YO)
Unlock all songs in Quick Play (YO) (RB) (RO) (GB) (RY) (YO) (RY) (RB) (GY) (GY) (YB) (YB) (YO) (YO) (YB) Y R (RY) R Y O
Unlock Everything (no sound plays when you enter these chords) (GRBO) (GRYB) (GRYO) (GYBO) (GRYB) (RYBO) (GRYB) (GYBO) (GRYB) (GRYO) (GRYO) (GRYB) (GRYO)