modify 2D arrays

I tried a lot of stuff, but I don't know how to assign new values to arrays inside arrays efficiently. I know how to assign single values to one point of the 2D array, but I am working on a code, where it would use up most of the memory just assigning values.

Anyone has some suggestions for me?

int array [3] [2];  //initialzie a 2D array

void setup(){
  array[1] = {1,2}; //assign an array to the second part of the "root" array.

void loop(){

I would also be happy if i could reassign the whole 2D array, like:
array = {{2,3},{1,2},{4,5}};

Have you considered using memcpy?

Have you considered using memcpy?

I am not sure what memcpy is...

Try here