In the first printing of the 1892 RLDS edition, the compositor set “in the days that the word of the Lord came unto us”. In a subsequent printing from the 1892 plates, the correct singular day was restored to the RLDS text. This correction could have been made by reference to the language of the preceding verses and without reference to any prior edition:
Summary: Maintain in Helaman 13:36 the singular day in the phrase “in the day that the word of the Lord came unto us”, the reading of the earliest textual sources.