JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
When you say sub-header are you referring to the text below the header? Or are you referring to the sub-labels?
Header and Text - You can edit the text by clicking the "Edit Html" once you select the field.
Sub Label - You can adjust the font size by applying custom CSS code. We can help you that.
Hope this answered your question.