Hello. My name is, Mike. I'd like to try and assist you with your question. All of the accounts (iTunes, iCloud, etc.) are associated with an Apple ID. The passwords are unique to the specific Apple ID and not to the device. It is absolutely possible to associate all of your Apple devices (iPad, iPhone, iTunes, iCloud, etc.) with a single Apple ID. You just need to change this information under the settings option of the your devices. So once you update the settings so all devices use the same Apple ID, then they will all share the same password ***** with that Apple ID for the purpose of using iTunes and iCloud.