We are sorry for the trouble. Would you mind sharing more details about the issue you are experiencing?
Are you creating the PDF file or are you creating the PDF form? Please share the steps you are doing to prepare the PDF for a better understanding.
If you are preparing the PDF form and trying to change the font in the text boxes, make the changes to one box, and then right-click it with the Object Select tool and select "Use Current Properties as New Defaults" and see if that works for you.
Let us know if you are referring to something else.