Use SharedPreferences to save login data, but it jsut can only save one

i have used SharedPreferences to save the login data likes remember me,

and i had set three button it has save, clear, read function inside,

but after i save one login data, i cant update the save information anymore,

By the way i already set one checkbox to save data

but it looks doesnt work as well ..

Could some one help me to solve this problem ?

here is my code :

package com.example.escanui;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;
import android.widget.MultiAutoCompleteTextView;

public class UserInfoActivity extends ActionBarActivity {

    public MultiAutoCompleteTextView userName;
    public MultiAutoCompleteTextView ipAddress;
    public Button loginConfirmBtw;
    public EditText passWord;
    public CheckBox memUserInfoCb;
    public Button save, read, clear;

    private SharedPreferences settings;
    private static final String data = "DATA";
    public static final String nameField ="NAME";
    public static final String passwordField = "PASSWORD";
    public static final String ipField = "IP";
    public static final String filePathFile ="FILEPATH";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_user_info);

        ipAddress = (MultiAutoCompleteTextView) findViewById(R.id.multiAutoCompleteTextView1);
        userName = (MultiAutoCompleteTextView) findViewById(R.id.multiAutoCompleteTextView2);
        passWord = (EditText) findViewById(R.id.editPassword1);
        loginConfirmBtw = (Button) findViewById(R.id.loginButton);
        memUserInfoCb = (CheckBox) findViewById(R.id.checkBox1);
        save = (Button) findViewById(R.id.saveBtw);
        read = (Button) findViewById(R.id.readBtw);
        clear = (Button) findViewById(R.id.clearBtw);

        setEventListener();


        if (memUserInfoCb.isChecked())
        {
            saveUserInfo();
            readData();
        }else{
            ipAddress.setText("");
            userName.setText("");
            passWord.setText("");
        }
    }

    public void readData()
    {
        settings = getSharedPreferences(data,0);
        userName.setText(settings.getString(nameField, ""));
        ipAddress.setText(settings.getString(ipField, ""));
        passWord.setText(settings.getString(passwordField, ""));
    }

    public void saveUserInfo()
    {
        settings = getSharedPreferences(data, 0);
        settings.edit().putString(ipField, ipAddress.getText().toString());
        settings.edit().putString(nameField, userName.getText().toString());
        settings.edit().putString(passwordField, passWord.getText().toString());
        settings.edit().commit();
    }

     public void setEventListener(){
            save.setOnClickListener(new OnClickListener(){

                public void onClick(View arg0) {

                    saveUserInfo();
                }
            });
            read.setOnClickListener(new OnClickListener(){

                public void onClick(View arg0) {

                    readData();
                }
            });
            clear.setOnClickListener(new OnClickListener(){

                public void onClick(View arg0) {

                    ipAddress.setText("");
                    userName.setText("");
                    passWord.setText("");
                }
            });
        }
}