Jamieson, Fausset and Brown on 2 Corinthians 2:15

15. The order is in Greek, "For (it is) of Christ (that) we are a sweet savor unto God"; thus, the "for" justifies his previous words (2Co 2:14), "the savor of His (Christ's) knowledge." We not only scatter the savor; but "we are the sweet savor" itself (So 1:3; compare Joh 1:14, 16; Ep 5:2; 1Jo 2:27).

in them that are saved--rather, "that are being saved ... that are perishing" (see on 1Co 1:18). As the light, though it blinds in darkness the weak, is for all that still light; and honey, though it taste bitter to the sick, is in itself still sweet; so the Gospel is still of a sweet savor, though many perish through unbelief [Chrysostom, Homilies, 5.467], (2Co 4:3, 4, 6). As some of the conquered foes led in triumph were put to death when the procession reached the capitol, and to them the smell of the incense was the "savor of death unto death," while to those saved alive, it was the "savor of life," so the Gospel was to the different classes respectively.

and in them--in the case of them. "Those being saved" (2Co 3:1-4:2): "Those that are perishing" (2Co 4:3-5).