Hi soojung,
I suggest you to check with the debugger what CSS is added to the Text. My best guess is that some CSS is inherited from your web page, because such alignment is not present on our website DropDownList widgets.
You can use selectionRenderer callback.
It’s a callback function which is called when the selected item is rendered in the jqxDropDownList’s content area. By using the selectionRenderer function, you can customize the look of the selected item.
Here is a demo.
Best Regards,
Peter Stoev