When you search for words in a PDF, the search includes any text appearing in form fields (as well as other text in the PDF), whether you typed the text or selected it from a list or menu on the form.
Type the text you want to search for in the Find box in the toolbar, and then press Enter. To find the next instance of the search text, press Enter again.
Choose Edit > Search, and type the text into the Search window. Then select other basic or advanced options for searching, and click Search.