iCloud.com Address Book Not Displaying Custom Fields Correctly

I have set custom fields and selected a specific default layout on my Address Book fields on my Mac (Mavericks). However, when I come to iCloud and on my PC's, I lose that ability to customise the default fields and the custom fields that I have are shown as their default values. E.g. Instead of the custom names it is shown as facebook, twitter etc. This was customised using my Mac. Please advise.

Thanks!