Change "iCloud" description name in iOS Mail???

When opening Mail in iOS, under "All Inboxes", there is a list of all my email accounts, including my Apple account entitled "iCloud". I'd like to change the description name of the "iCloud" email account to something else. I'm running iOS 9.0.2. (I'm easily able to do this in Mail on my Mac, just not on the iPhone.)

Can anyone share how to change the iOS Mail "iCloud" description name?

Thanks for your help!