Editing The Registration Page
You Can't Change The Form Without Buying a Premium Account (CP>Paid Services>Paid Services).
After Buying One You Need to Go To CP>Users(Left Panel)>Module Settings>Local Users. That's How Can You Edit The Registration Form.
Remove The Security Code From Whole Site
CP>Users(Left Panel)>Users Group>Set Permissions For All Users>Other>No Security Code Required
Changing The Language
uCoz Doesn't Support Vietnamese Language
CP>Settings>Common Settings>Site Language
