Hi Shantell, these are populated via flow steps in smart campaigns. If you need to find the specific campaigns that are attributing lead source, you can look at a lead's record and see which smart campaign updated their lead source. It might be a global campaign, or it could be local to each program.
Fortunately or unfortunately, there aren't any standardized values or standardized picklists for these values so they don't need to be amended by an admin.