[RMXP] CHANGING THE CONTROLS????

I could really use some help here! For the keyboard controls, I want 'z' to be the action button, not 'enter'. How do I change this? I've seen most people say you can only do it in the script, so if that's true, which script do I go to? Whenever I pull up scripts, there's so many things to choose from! Also, I have no idea how to do scripts, so could you tell me exactly what to do when I do find the correct place to go? Pleeeease? Thank you so much!!