Android : android Dynamically change theme to all activites and fragments

in my main activity there is buttons to change themes its work just for this activity by this method

case R.id.button1:
            Utils.changeToTheme(this, Utils.THEME_DEFAULT);
            break;
        case R.id.button2:
            Utils.changeToTheme(this, Utils.THEME_WHITE);
            break;
        case R.id.button3:
            Utils.changeToTheme(this, Utils.THEME_BLUE);
            break;
        case R.id.button4:
            Utils.changeToTheme(this, Utils.THEME_PINK);
            break;
        case R.id.button5:
            Utils.changeToTheme(this, Utils.THEME_RED);
            break;

and I want it to work in other activity too and when I add

setTheme(R.style.Theme_PINK); 

to other activites its stop working

public class MainActivity extends FragmentActivity implements
        ActionBar.TabListener {

    private ViewPager viewPager;
    private TabsPagerAdapter mAdapter;
    private ActionBar actionBar;
    // Tab titles
    private String[] tabs = { "5th Grade", "4th Grade", "3rd Grade", "2nd Grade", "1st Grade" };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        // Initilization
        viewPager = (ViewPager) findViewById(R.id.pager);
        actionBar = getActionBar();
        mAdapter = new TabsPagerAdapter(getSupportFragmentManager());

        viewPager.setAdapter(mAdapter);
        actionBar.setHomeButtonEnabled(false);
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);        

        // Adding Tabs
        for (String tab_name : tabs) {
            actionBar.addTab(actionBar.newTab().setText(tab_name)
                    .setTabListener(this));
        }

        /**
         * on swiping the viewpager make respective tab selected
         * */
        viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

            @Override
            public void onPageSelected(int position) {
                // on changing the page
                // make respected tab selected
                actionBar.setSelectedNavigationItem(position);
            }

            @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {
            }

            @Override
            public void onPageScrollStateChanged(int arg0) {
            }
        });
    }

    @Override
    public void onTabReselected(Tab tab, FragmentTransaction ft) {
    }

    @Override
    public void onTabSelected(Tab tab, FragmentTransaction ft) {
        // on tab selected
        // show respected fragment view
        viewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabUnselected(Tab tab, FragmentTransaction ft) {
    }

}

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