Starting in Season 6, it took place in Blue's Room with Blue in her puppet form. Because of Blue in her puppet form, she does not bark "Bow Bow Bow!" after Joe says, "Come on in!". However, it appears by accident in the season 6 episode Playdates. After Blue grabs the book, Moona comes in and changes Blue to her animated form, and then she jumps in the book and the rest of the intro plays as normal.
This theme is only used during the seasons with Joe as the host.
Steve never sings this song with everyone because he's at college and is absent for almost the whole series but still appears more a couple times.
Blue opens the book in the beginning, but she's still in it when it closes. It's also not on the shelf when it closes, it is still on the ground. It is unknown who puts the book back on the shelf or how Blue gets out of the book for the next theme song every time.