When you're prompted to enter your birthday when signing up on the Family Express® app through an Android phone, it begins with a calendar view. Don't wear your finger out tapping the back arrow from month to month! Simply tap the date at the top to scroll backwards through the years.
As of now, this seems to be an Android function we're stuck with, but we're working on a more intuitive way of entering your birthdate in the future.
For iPhones, start with the year.