When you type over a field in a legacy form with the form unprotected, you replace the field with your text.

The form you uploaded does type in all caps and underlined with protection on. The grey says it is a field.

Question:

Do you want people to only be able to enter information in your form fields? If so, you want a protected form. If you want them to be able to type anywhere, then you do not.

You could create an on-exit macro for protected fields that, upon leaving the field unprotects the form, unlinks the field (giving you what was typed, but not in a field) and reprotects the form. Of course that makes every answer (even blank) a final answer. Why do you not want people to be able to change or edit answers?