Upon using Microsoft 365 for the first time, you may notice that names in your address book are in two different formats, some with last name first, the others with first name first:
Example:
Smith, John
or
John Smith
Typically names saved in the format FIRSTNAME LASTNAME are displayed that way because they were saved in that format when they were added from the Exchange Global Address List to your IPhone. This format for that entry was then passed along to your exchange.ou.edu address book.