The default address is not being selected when you purchase labels, and labels are printed with the wrong address.

The sender address feature in itself is confusing and appears hidden, meaning you don't know what it is until its too late. The full sender address should be visible during the label purchasing process so it can be changed if it is wrong. Once you start to select label, before checkout, you can no longer change the sender address which sucks. It should be easily edited up to payment point.