On the Home screen, tap one of the 5 big cards: Scan with Camera, Sign a PDF, Password Protect, PDF Converter or Extract Text (OCR).
Tap Choose files and select all the files you need (you can select several at once).
Choose Word.
Optional: to convert only some pages, type them in Specific pages (for example 1-3,5). Leave it empty for all pages.
Tap the big purple Start button and wait a few seconds.
When you see Done!, tap Download. The new file is saved on your phone or computer.
Note: a scanned PDF is only a picture, so it has no real text. Run Extract Text (OCR) first if Word/Excel comes out empty. Complex layouts may change a little.