From http://www.toodledo.com/info/help.php?sel=74
Toodledo's iPhone App supports most of the fields that we have on our main website. Some of these fields are disabled by default, but it is easy to enable fields you want to use and disable fields you don't want to use.
Inside our iPhone app, tap on "Settings" and then tap on "Fields & Defaults". This page allows you to reorder your fields and move fields from the "unused" section to the "used" section or vice versa. Just tap on the "reorder" button and then drag the fields around to suit your needs.
This page also allows you to set default values for each field.