editing the ckeditor config.js has no impact

I changed my CKeditor config.js file to include all the buttons possible to this:

CKEDITOR.editorConfig = function( config ) {
    config.toolbarGroups = [
        { name: 'document', groups: [ 'mode', 'document', 'doctools' ] },
        { name: 'clipboard', groups: [ 'clipboard', 'undo' ] },
        { name: 'editing', groups: [ 'find', 'selection', 'spellchecker', 'editing' ] },
        { name: 'forms', groups: [ 'forms' ] },
        '/',
        { name: 'basicstyles', groups: [ 'basicstyles', 'cleanup' ] },
        { name: 'paragraph', groups: [ 'list', 'indent', 'blocks', 'align', 'bidi', 'paragraph' ] },
        { name: 'links', groups: [ 'links' ] },
        { name: 'insert', groups: [ 'insert' ] },
        '/',
        { name: 'styles', groups: [ 'styles' ] },
        { name: 'colors', groups: [ 'colors' ] },
        { name: 'tools', groups: [ 'tools' ] },
        { name: 'others', groups: [ 'others' ] },
        { name: 'about', groups: [ 'about' ] }
    ];
};

This config was generated using the CKeditor config generator tool.

After the change was deployed to my server and the page was refreshed using incognito mode in chrome non of the buttons changed.

If i add this code directly in my admin.master then the new button does show.

<script>
        jQuery(function() {
            CKEDITOR.config.extraPlugins = 'justify';
        });
    </script>

Is it possible that i am not using the config.js at all?

from editing the ckeditor config.js has no impact