The title of "Ecclesiastes" is the Greek version of the Hebrew title "Koheleth." People have plenty of different ideas about what the word means, exactly. It's traditional to translate it as "The Teacher" or "The Preacher," but more literally, it means "The Gatherer," "The Assembler," or "The Assemblyman." Scholars seem unable to make up their minds about how we're supposed to understand this. Does it mean that Ecclesiastes gathered together or assembled these sayings? Or does it mean that he would gather people together to teach them these sayings (or others like them)? No one is totally clear on this. But it probably means at least one of those two things.