Rest Days

Is there any way to change your rest day to another day?|||If you go to the 30 day challenge even if it is your rest day, the calendar will just scoot your rest to the next day. I think. I had clicked on it once on my rest day, wound up backing out of it, but I think when I looked at the calendar at that point it just showed 3 days on, day of rest and then back to the 2 on 1 off.