how do you change the text size for the sub label?

I'm trying to make the size of the sublabel larger its too tiny can't read it. how do you do it. the form style only is changing the main question size. and Is there a way of adding a sub label right underneath the question instead of under the text area box? 

You can increase the font size of the sub label. Please inject the following custom css code to your form. (You can customize the px number accordingly)

.form-sub-label {
      font-size: 12px !important;
}