I am a live person. Which Adobe software or service are you using?
PDF is typically an export function. In other words, the native document is created in MS Word, InDesign or some other app and then exported to PDF for distribution. Although some minimal editing can be done in Acrobat Pro, it's often best to edit the original file in Word, InDesign, etc.. and then export to PDF again. That said, it's hard to make suggestions without knowing more about what you're doing.
The second half of your question is unclear. Download from where? With which tools?
Nancy O'Shea, Adobe Product User & Community Professional Alt-Web Design & Publishing ~ Web : Print : Graphics : Media