Here in the printer’s manuscript, Oliver Cowdery initially wrote even; perhaps he was influenced by the preceding occurrence of even in this verse (“and even all the prophets”). Somewhat later, Oliver corrected the even to ever (the level of ink flow is only slightly heavier). His correction may have occurred almost immediately, after redipping his quill, or perhaps later when he proofed 𝓟 against 𝓞. The use of even in the phrase “even since the world began” makes little sense in this context. In addition, other passages that refer to the beginning of the world use ever rather than even:
For further discussion of the potential confusion between ever and even, see the discussion under Mosiah 4:7.
Summary: Retain in Mosiah 13:33 Oliver Cowdery’s correction in 𝓟 of even to ever in the phrase “ever since the world began”; the text consistently uses ever rather than even for this phrase.