-----Description-----  
This task involves updating an element within a 2-dimensional array. The goal is to modify only a specific inner array by changing one of its elements to a new value while keeping every other element and all other inner arrays unchanged.

-----Input-----  
The input consists of:  
• arr: An array of arrays of natural numbers.  
• index1: A natural number representing the index in the outer array identifying which inner array to modify (0-indexed).  
• index2: A natural number representing the index within the selected inner array that should be updated (0-indexed).  
• val: A natural number which is the new value to set at the specified inner index.

-----Output-----  
The output is an array of arrays of natural numbers that:  
• Has the same overall structure as the input.  
• Contains all original inner arrays unchanged except for the inner array at position index1.  
• In the modified inner array, only the element at index2 is replaced with val, while all other elements remain the same.

-----Note-----  
It is assumed that index1 is a valid index for the outer array and that index2 is a valid index within the corresponding inner array.