When scribe 3 of 𝓞 first wrote the name of Laban’s servant, he wrote it distinctly as Zoram. But his two subsequent spellings in 𝓞 read Zorum—that is, with a u vowel rather than an a vowel. Oliver Cowdery’s spellings of the name in 𝓟 can be read as either Zoram or Zorum (that is, the last vowel is a partially closed a). The printed editions consistently have Zoram:
Evidence throughout the original manuscript suggests that the scribes took care to spell the first occurrence of a name correctly, as here in 1 Nephi 4, with the understanding that even if subsequent spellings of the name varied, the correct spelling could be recovered from the first occurrence. This point about the spelling of names is discussed thoroughly in volume 3.
The Book of Mormon has three different individuals named Zoram and two different peoples referred to as Zoramites. In two places in 𝓞, Oliver Cowdery wrote a partially open a in Zoramites so that the word could theoretically be read as Zorumites. But everywhere else, he consistently wrote the vowel as a clear a.
Also related to Zoram are two compound names: (1) Cezoram, found three times in Helaman 5–6, and (2) Seezoram, found three times in Helaman 9. The original manuscript is not extant for any of these, but in the printer’s manuscript Oliver Cowdery always spells the names as Cezoram and Seezoram—that is, both consistently end in zoram, with the a vowel. Thus the evidence from these two names also supports the spelling Zoram.
Summary: Scribe 3’s spelling in 𝓞 of the first occurrence of Zoram has the a vowel, which apparently represents the correct spelling, not the u of his two subsequent spellings in 𝓞.