Comparison of the original 1830 Book of Mormon vs the 1966 and later published copies of the Book of Mormon

In studying the 1830 publication alongside the 1966 publication, I've discovered a lot of changes in words and phrases. If a Book is purported to be inspired by God (such as the Bible) is it not logical to expect it to not need "improvements?" Does not the existence of these changes demonstrate that indeed neither the original 1830 version nor the 1966 version are inspired or God breathed? And if one does believe that God can change his revelation to man, how then can we know and trust that it won't change again and again like shifting sand? Isn't God by nature immutable? And therefore shouldn't his word to us also be unchanging?