Problem when use CheckboxSelectMultiple in admin page manager

I have a problem when trying to use this form CheckboxSelectMultiple to manage the “Manager” and can not expand the layout from the red square i need to expanded it to equal the green square or is there a solution to write the text in a single line because now it is hard to see and the name.It should be “Administrator - Smartapp Service”
It became “Administrator -
Smartapp Service”