Why can I not change my goals!

Apple watch has 3 pre-set 'Goal' rings. These are not necessarily my goals, but Apples goals for me. The standing ring is simply useless to me as a daily activity audit. I would much prefer steps as a goal given that I am contractor and am on my feet all day. Any activity related to cardio would be a better metric than whether or not I have attained an erect position once in an hour. Why can I not change the actual goals to better reflect my lifestyle on this rather expensive device? Seems like a simple option to create.