MarchieB:
Where it says "Wedge de Arena (obligatario)" that's your irons ... change that one!
You cannot put irons in any of the "opcional/optional" slots. They have to be put into the "obligatario/required" slot.
I wonder how he could put a sand wedge in the slot solely reserved for an iron set in the first place. I just checked it on the app and I can assure you that it cannot be done. You can equip nothing but an iron set in that slot.
EDIT : Based on the OP's profile, it looks like his problem got sorted out fortunately. Do you mind sharing how it was fixed, Juan? :)