Adding a currency in numbers missing custom format option
I just paid for numbers latest version June 2012. iPad 3' v5.1.1. Want to format a cell as a currency not in the little list chosen by apple. Forums suggest using the custom format option but I can not see this anywhere? Any ideas how to add a custom format or how to extend the list of currencies to all currencies. If nothing else missing out a countries currency as too unimportant to include is just plain rude!
iPad, iOS 5.1.1