madkite

You need permissions to write to the "/system" partition. Some stock firmwares disallow this. Some phones even lock this in hardware. Search on forums like xda how to unlock it on your specific phone model.

Did you get write access to /system? Are you able to copy files into /system via root explorer? Do programs like AdAway work fine?

Your device is locked by manufacturer and you haven't write access to "/system". In other words you have "half root". Read topic on xda related to your device.

Credit cards aren't stored on device. And there is no way to retrieve full number of credit card from Google. And?