If you go to your Start page, in Step 1 you'll see the button to track your weight and a link to edit your weight loss goal next to it. You can click there to update your numbers.
Hope that helps,
"You may have a fresh start any moment you choose, for this thing that we call "failure" is not the falling down but the staying down." Mary Pickford
"No matter how slow you go, you are still lapping everybody on the couch."