Don't have an answer to main question. Seach, though, is one of the options on the ribbon along the top.

I would look into some of Greg and Dian Chapman's writings. I suspect this question has been around as long as Word forms. This page will give you some links. Look under Additional Written (and Web) Resources near the top. The page, itself, will not answer your question.
Making Forms with Microsoft Word

To help those who know more than I assist you, can you detail how you are creating your form?
- Content Controls?
- Legacy form fields in a protected form?
- ActiveX controls?