I am not sure how to move the unsubscribe box next to the text field, but if you click on the unsubscribe in the editor you can drag it back and forth.
I don't believe you can do this through the visual form editor UI. You will probably have to insert some custom CSS to align the submit button where you want vertically.
In Chrome you can right-click on the button and then click inspect element. This will show you id and class of button. Then you override default styling of button.