The design for iPhone - intuit ivory
I think, while adding a new bill... The steps should be
--- to add the bill
--- to add the people involved
--- to split the amount per share .
This may not be a great change to the app but for the app to exist the bill is the start point. So,the process of adding the bill should be first and then the people involved and later the share percentage.
The design pattern should be a little changed.

Thanks for the suggestion! Actually, this is something we’ve tested quite a bit – different people have different intuitions about how to order the bill’s cost, the description, the people involved, and the amount per share. We tested a variety of different orderings before settling on the current order, so we’re unlikely to change it in the near future. I’m very sorry for the trouble!