- Do not protect the document for filling in forms. Instead, restrict to certain styles. Filling in forms is the most restrictive type of editing restriction with a number of problems. It is there for use with legacy form fields.
- Provide styles that meet your users' needs. That would include styles that have shading (not highlighting). Highlighting cannot be a part of a style. Shading can.)
If you are using legacy form fields, unless there is a reason to continue with those, use Content Controls instead. (Do not mix.)
Create a Form Using Word Content Controls