PDF files can be edited in Word, sort of…

I am unsure which steps you have followed. Suzanne has given specific instructions for using OneNote.

How was the file created originally, and by which program? It could have been created from a scan or a picture taken by a phone camera. Those are pictures of words saved as pdfs. Just as you can have a picture of a car. You can see the car in the picture, but you can't change the timing of the engine in that picture. You can't change the order of text or otherwise edit it with a picture of text. Word can open such a file, but it can't edit it. You have a Word file that contains a picture of text rather than text.

In that case, you need to convert the picture to text. This is a process known as optical character recognition. This is built into Adobe Acrobat (but not the free Acrobat Reader) and is also in Office OneNote. Most scanner software comes with an OCR component as well. Word does not have OCR capability. OneNote does.

• Copy text from pictures and file printouts using OCR in OneNote
• How to OCR a PDF in OneNote

Once translated into text, it can be edited in Word but there will still be formatting anomalies.

If you simply want to write on the document (but not in it) you can add a Text Box floating on top of the document layer, whether or not it has been put through the OCR process.

Web pages or Word documents that have been saved as PDF will not need the OCR process, they retain their text, although not all their Word structure and formatting. Documents created as PDF from other programs will likely be even more problematic.

Finally, documents converted from pdf (or really any other format) to Word can be tough to edit because the conversion process never has a one-to-one matching of how formatting is done under the hood. This means that a converted document will seldom be formatted in Word in a way that uses Word features well for that formatting. An example is multiple section breaks to change margins, where in Word you would simply change the paragraph indent. Margins and Indents in Word. Another example is that Word formatting of text is best done using Styles and those will not be used. It will all be direct formatting. That can make a huge difference in how easy it is to edit. The Importance of Styles in Microsoft Word.

If possible, find the file from which the pdf was created and edit that file, using the program that created it. Then if you need it in Word format and it is not, convert it directly to Word. This will cut out one conversion process and make for fewer editing problems.

When I really need the document in Word format and intend to do much editing, I create a new Word file and paste the content into it as plain text. Then I format it to match the original using Styles for the formatting as much as possible. This takes time; for me, it is worth it and saves a lot of frustration.