Why some PDFs "rotate back" after you fix them
Many PDF viewers let you rotate the on-screen view without changing the underlying file — close and reopen it, or open it in a different app, and it's sideways again. That's a display-only rotation, not a real fix, and it causes problems the moment someone else opens the file or it gets merged with other pages.
PrivaPDF writes the rotation permanently into the page's internal orientation data, so the fix travels with the file regardless of which app or device opens it next — useful for scanned documents where half the pages came out landscape and half portrait.