Bought Samsung Galaxy II in China, need to change alerts, etc. to English
You could get a US/UK Firmware from samfirmwarec.com and flash it with heimdall / odin. But you will lose your warranty and I can not guarantee that it will work (it could even leave your phone in an unusable state).
Flashing can be done with three easy steps:


get your phone in download mode
connect it with usb
configure heimdall/odin and start the process 


There are some other things that you need to be aware off, but everything is documented in the links I included. Maybe you son will also help you. :)