how to ammend the second newest commit
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I know you can do git --ammend to change the commit message of the latest commit. But how do I change the second newest commit message.. Here's what my commit looks like now:

    commit eca1b2db14da8ace66aed172056c6e7aaf323093
    Author: Adam Sandler
    Date:   Fri Jul 13 18:00:13 2012 -0700
    
        Pre-final work on appending new items on top
    
    commit 7d21bbfea24cb72eafbe0213cad6339354078a81
    Author: Adam Sandler
    Date:   Fri Jul 13 11:57:40 2012 -0700
    
        Pre-final work on appending new item on top.
        
        Loading more  when user reaches the end of the scroll view

I want to change the commit `7d21bbfea24cb72eafbe0213ca` that has two message in it.