i = 1
while i != 3:
  if i == 1:
    def main3():
      decision3 = str(input("Do you accept? (Yes or No)"))
      if decision3 == 'No':
          print("narration")
      elif decision3 == 'Yes':
          print("narration")
          i = 2
      else:
          print("Sorry, that is an invalid input. Please re-enter.")
          main3()
    main3()
  else:
      i = 3
      print("narration")

if i == 1:
    def main3():
      decision3 = str(input("Do you accept? (Yes or No)"))
      if decision3 == 'No':
          print("narration")
      elif decision3 == 'Yes':
          print("narration")
          i = 2  # <-- This does nothing to i outside of main3()!
      else:
          print("Sorry, that is an invalid input. Please re-enter.")
          main3()
    main3()  # <-- This is the problem!