Under the Water Days or Days to Water dial position on your controller you have three options. You can have the program run on specific days, an odd/even schedule, or an interval schedule.
To move out of the Interval mode and back into one of your other two options simply continue pressing the right or left arrows. Eventually you should either see a or above the individual days. Now you are in Day of the Week mode and the days of activation will need to be chosen.
The button will move your blinking selection icon from day to day, the will activate a day, the button will deactivate a day.