How to change first-billed producer on mobile?

I think the reason is actually that this field in the Overview tab only includes people listed as "producer" or "produced by", not "lead producer", "executive producer" or anything else.

Jared: In addition to what Peter mentioned, I would note that since your film is not released yet, you can still change the on-screen credits before it is released. If you and Deana Taheri are supposed to have equal status, then you can both have the credit of "producer" and she should be listed before you in all circumstances on IMDb because her name precedes yours alphabetically. If Deana is supposed to have a superior producer credit to yours, then she should be the "producer" and you can take a lower-status title such as "co-producer". As indicated at https://contribute.imdb.com/updates/field/producers/job?, "lead producer" isn't one of the 50 most common job titles for producers so it won't necessarily be considered as meaningful as "producer".