Now that you've opened up the collections list you will notice 3 MissionPlaythroughData the first one is Playthrough 1 (Normal Mode), the second one is Playthrough 2 (True Vault Hunter Mode), and the third one is most likely the 'Something Interesting thing' that Gearbox Is planning on when they raise the level cap which will be a Playthrough 3 no doubt. Image below will give assistance if needed. When you find, it navigate your way to the arrow that will open up the collection window.
Now scroll down until you see MissionPlaythroughs.
Firstly you will need to open your save into Gibbed's Borderlands 2 save editor and move your way to 'Raw' to edit your characters Raw Data.
