wordpress中的屏幕选项不适用于新的自定义元框

I have created a meta box named "My Custom Settings", it is under post in wordpress with one input text box field. In the above to that post page I have seen the screen options menu with predefined "show on screen". After adding my new "My custom settings" meta box, it also available in that screen options. I have created a meta box named "My Custom Sett