How to update Minecraft to 1.7.4?

I'm having trouble updating my Minecraft client to 1.7.4. It is on a older version but each time I try to open the game, it loads to the old version even after I download the latest software.

I took a screenshot (or screenvideo… Whatever you want to call it) and posted it here:

http://screencast.com/t/rZJvwB5sr

(I forgot to turn my music off. Sorry).

I had the same problem except getting from 1.5 to 1.6. It's actually very simple. First open minecraft, but don't start it. Towards the bottom left of the screen it should say profile options or something like that. So click on that and on that thing it should say whatever version your on at the middle-bottom. Click that and choose the version you want. Hope this helped!