Some songs on the game actually has hidden difficulties that were not included, whether they were actual steps or just for testing. This glitch allows you to view these steps.
To start, begin by going to Oni Mode or Nonstop (The example is for Oni). Highlight the course you would like to play, such as Naoki-Neo Standard. Do not mind about difficulties now, the songs are what matter in the course you're planning to play. Next, highlight the course before or after it. The courses adjacent to the one you're aiming to play are what the songs' difficulties going to be. Legend Road, for example, which is adjacent to Naoki-Neo Standard, has four songs, on Heavy, Heavy, Heavy and Oni. Now, to do this correctly, start off at Legend Road, then press the right arrow once. The screen will change banner, but in a very quick time, the difficulty won't change (It will after a quick moment). When the banner instantly changes, but the difficulty does not, hit the green button (Start). If succesful, you shall be playing Aoi Shoudou on Heavy, and the rest. Of course, this is just an example, this glitch can work for any course, as long as the difficulties for each one are different. Be warned, some songs (Mostly the DDR Max2 Challenge games) will crash the game, and will need a manual restart for it to work.
Song Compatibility Edit
Here is a list of songs that have actual different effects when the glitch executes successfully.
Songs with Hidden Difficulty
Love Love Shine (Challenge)
Dam Dariram (Challenge)
Last Message (Challenge)
Drop Out (Nonstop Megamix) (Heavy)
Higher -Next Morning Mix- (Standard/Heavy)
My Summer Love (Tommy's Smile Mix) (Heavy)
Dam Dariram (Challenge, Double)
Aoi Shoudou (Challenge, Double)
Drop Out (Nonstop Megamix) (Heavy, Double)
Songs that will not function correctly
Aside from all of the Max2 remixes stated above, all Challenge Remixes will crash if playing on a different difficulty.
pkmnx, for having a very comprehensive list on how to do the glitch, and what songs can crash or work.