Why does fill and sign uses different fonts in the same document and how to change the font?

Hi,

Would like to know the exact version of the software & OS installed in your system.Also check whether is there any update is available for the software after going through "Help > check for updates "

Reset the preferences setting using this thread https://forums.adobe.com/thread/1595848

Is this happening with this particular document or with others as well.

Is this document is over network drive or browser interface, please save this to Local drive & then check what happens .

Also refer to this KB article for more information on this :- https://helpx.adobe.com/reader/using/fill-and-sign.html

Regards,

Yatharth