Being an Adobe hosted user site for Acrobat Answers it'd be rather inappropriate to get into discussions about third-party applications. Scansoft support would be an appropriate venue for questions about that application.
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Regardless of the PDF processor used (Acrobat, Adobe Reader, others) a scanner's output is an image of text not text itself. So, nothing for a "find" or "search" to grab.
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Use Acrobat to develop an OCR output for the scanned image of text in a PDF. This will provide something for Acrobat's / Adobe Reader's find / search to grab.
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Be well...