While a document is already published and is in the pre-press stage, as the recipient or the creator, you may be asked to make changes to it. You may, for example, be asked to do a bit of PDF text editing, or image editing.
Unfortunately, making changes to PDF content does not come as easily as they do in a Word document. Same goes for the flexibility you have with image editing. Some secured PDFs actually prevent it. However, if you have a PDF that allows it, there are a couple of editing options available.