Your overall rating does change when you win or lose a game in a tourney. While you remain in the room in which the tourney is taking place you will only see your score for the tourney, but once the tourney is over and/or you return to another room, you will see that your overall rating has changed.
This is the reason that many higher rated players have been reluctant to participate in tourneys. It's not always a good deal for your overall rating. If you lose to a much lower rated player, you take a big hit that takes a number of wins to recover from.
Personally, I would like it better if there was no effect on overall ratings for tourney games.