do we have to print our boarding pass or on our phone is accepted??? thanks

TSA Security and the airlines (if they offer an app) allow your phone's "Boarding Pass" to be used. Make sure it says "Boarding Pass" on your phone's airline app, and not just the flight information screen.

They do, make sure the backlight is all the way up and your screen is not cracked

Most of the airlines will let you use your phone.