Click on the star icon located next to the name of each goal to prioritize a goal.
To turn off the star, click on it once again.
The Star icon is also located on the bottom of the detail page of a goal, and it works same as the star icons on the list page.
Note the option in the action bar at the bottom. Once you click on it, you will be able to see your starred goals.
The option filled with purple means that only starred goals are displayed. To see all goals, click on it once again.
You can use the Sort icon in the action bar to automatically move the starred goals to the top/bottom of your list by dragging it to the desired position.
* For more information about How to Sort Goals, click here