As discussed under Alma 5:47, the plural manifestations (the corrected reading in 𝓟) is most probably the original reading here in Alma 7:17. In addition, we should note that the phrase “the manifestations of the Spirit /spirit which is in me” can be theoretically interpreted in two ways. In one case, the word Spirit (capitalized) refers to the Spirit of God. In the other case, the word spirit (uncapitalized) figuratively refers to Alma’s own spirit. The 1830 compositor left the word spirit uncapitalized (it was uncapitalized in 𝓟), but the 1852 LDS edition and the 1874 RLDS edition capitalized the word Spirit, thus explicitly claiming that the reference here was to the Spirit of God. Support for the capitalized Spirit is found later on in this chapter, when Alma once more refers to the influence of the Spirit in him:
In this second case, it is virtually impossible for the text to be referring to Alma’s own spirit; rather, Alma is referring to the Spirit of the Lord testifying in him.
Summary: Restore in Alma 7:17 the plural manifestations; also maintain the capitalized Spirit (and, similarly, the capitalized Spirit in Alma 7:26).