Correction

Question

When it says my Arr[0][2] = 42 it is incorrect. It should be myArr[0][2] = 3

Answer 1

where is the full question

Answer 2

No, the code is NOT telling you that myArr[0][2] is equal to 42. It's just assigning myArr[0][2] to the value of 42. There's nothing wrong there.
The tutorial is simply showing you that you can assign the values of the multi-dimensional array individually.

Answer 3

if I suppose the question is
arr[][]={{1,2,3,4},{1,2,3,4}};
here we will say that 1st part is 0 and second is 1 so 0 and 1 both have more sub parts like 0 has 0,1,2 and three which are 1,2,3,4 respectively
So here is what we will conclude
arr[0][2]= 3
hope this helps you.

Answer 4

You should probably send this as feedback (from the app's menu)