Thank you for your post.
At this time, FileMaker Go does not have the ability to "freeze" the Header (or Footer) when you pinch and zoom the Body. I recommend that you enter this into our Feature Requests web form at:
The entries into this web form populate a database file that is populated by Development and Product Management where it is discussed and considered for future releases. Although I could easily copy your post and paste it into the web form, there are some questions asked that only you can answer.