A PDF opens and one page is sideways. Or every other page in a scan is upside down. You know how the pages should look; you just need a way to turn them and keep the result. That is what I do. Use the arrows on a page to turn just that page, or select several and rotate them together. Odd and even selection helps when the same problem repeats through a scan. You can undo a turn or return to the document's starting view before saving. I save the whole document as a new PDF, including the pages you did not select, in their original order. Your source file stays untouched, and the PDF is processed on your device. The turns are saved in the new file, ready for the next time you open it. My guides explain page selection, undoing changes, and what to expect from the saved PDF.