Walter W. Smith, RLDS historian, explains textual changes in the 1908 authorized version of the Book of Mormon.
Walter W. Smith, "The Book of Mormon, Its Translation and Publication," Journal of History 14, no. 1 (January 1921): 32
Concerning the prohibition of polygamy; book of Jacob, chapter 2:6, 7: “I must testify unto you concerning the wickedness of your hearts"; must, instead of might. 2:45: "Behold ye have done greater iniquity than the Lamanites, our brethren." Iniquity, singular form, specific; instead of iniquities in other editions. Ethel 1:16:
"The Palmyra and Kirtland editions both read, "thy families," referring to the brother of Jared and the commandment to migrate. The manuscript reads, "thy family"; the singular instead of the plural form of the word. The text was made to read according to the manuscript.