Hi Seank,
Sorry for the delay in response.
As you are have mentioned above, you are not able to change the font and color of the text you add in the PDF form.
You can only change the font and color of the text in the PDF form when there is a form field added to the PDF.
Also, if there are no predefined settings added on the PDF.
As you are using Fill And Sign to fill the PDF form, it seems there is no form field added to the PDF.
If you are using "Add Text" feature in Fill & Sign tool, sorry to say there is no option to change the font style and color.
It is a designed behavior.
You may change the text color you add in the PDF temporarily.
Open the PDF in the application and go to Edit > Preferences > Accessibility.
Check box for "Replace Document Colors" and then select the radio button for "Custom Color".
Select the text color and click OK at the bottom of the preference window.
The color of the text will change only for the PDF that you open in the application.
Check if that works for you.
You may share your suggestion on this over here Feature Request/Bug Report Form
Hope the information helps.
Let us know if you need any help.
Regards,
Meenakshi