Why do the later versions of the Book of Mormon contain added phrases that seem to change the nature of Christ? The original 1830  Book of Mormon contained statements to the effect that "Jesus Christ is God the Eternal Father" in three separate places (1 Nephi 11:21, 32, 13:40, source). Only recently did I discover that all later printings have this statement edited. I verified this fact with cover and page photos on the 1830 Book of Mormon website. Translation of the plates was claimed to be inspired, and when complete it was confirmed by God to be correct.

The official LDS view was that in 1837 the Book of Mormon was "versified" from paragraph form for convenience and corrected only in grammar and spelling. Why then was this statement edited by adding three words in the 1837 (and subsequent) editions to read "Jesus Christ is the Son of God the Eternal Father" thus changing its meaning in those same three places? 



1 Nephi 11:21:



Full page

1 Nephi 11:32:



Full page

Read 1 Nephi 11:21, 32 on LDS.org.



1 Ne. 13:40:



Full page

Read 1 Nephi 13:40 on LDS.org.



See other pages from the original 1830 edition.
Why did Joseph Smith change those verses? For clarity.

The December 1983 edition of the LDS-published Ensign magazine included the article Understanding Textual Changes in the Book of Mormon. The article addresses several types of changes including the specific ones asked about by the OP.


  In a few places, however, Joseph Smith did intentionally add to the
  text to clarify a point. An illustration of this is the added words
  the son of in 1 Nephi 11:21, 32, and 13:40. The text would be correct with or without the additional
  words, but the addition helps the reader avoid misunderstanding.


Eternal Father is a term that can correctly refer to Jesus Christ in contexts such as father of the church (1 Corinthians 4:15, Mosiah 15:11) and father of the creation (Helaman 14:12).

Apparently Joseph Smith, as translator of the Book of Mormon, wanted to clarify that those verses were speaking of Jesus Christ and not Christ's Father. It wasn't a change of doctrine but a change to avert misinterpretation.

For further reading, see this article.