"The song at the title screen, it sang: 'You're elected Charlie Brown!', but they should of sang: 'You're NOT elected Charlie Brown.'"
There's a reason for this; the first time it aired, it was called, "You're Elected, Charlie Brown," and used the theme music with that title. However, sometime after that, presumably somebody noticed that, as Charlie Brown wasn't actually elected, the title made no sense, so the title was changed, and the theme music changed to a different song without lyrics. (It is possible that the on-screen title was changed at the last second, but note that CBS commercials for the show's first airing used the original title.)