A solution that may help is to change the form layout to Labels on Top. This option is in a drop down menu in the toolbar at the top of the form edit mode (Design tab).
The first "column" of questions all share the same label width when the Label is on the left.
If you add field to the right of an existing element then its label can be adjected independently of the other fields on the form.
Jeff solution to change the Caption on Top might give you the design you want.