change font size in fillable PDF?

I cannot change the font in a fillable PDF.

I am filling in a government-issued form. This government requires me to use this form.

The form has many fill-in boxes. Many, many of the boxes in this form are too small to accommodate all the text that I must insert in the boxes.

The form insists on formatting the text as Helvetica, 24 point. I think I could get all the text in if I could reduce the size of the text to 12 point. But I have been unable to do so.

I have tried in both Preview 8.1 and Acrobat Reader (2015.) In both applications I click on the text that I have typed and push the Control key. Neither application has any tool in the resulting menu to edit the font.

I did find this tool in Preview’s Toolbox:

But this tool is ineffective, either as to text that I have already typed or text that I do type.

Am I stuck wih the font style and size set by the government?