I can't get comments to appear in pdf document when I click on comment balloons. This is also happening with documents that I used to be able to read the comment balloons in, before I upgraded to Windows 10 and Office 2013

You can display balloons for comments in Word documents from the Review tab
When you create the PDF from Word, if you want the PDF to display the balloons shown in the Word document, you must set the option from the save as PDF dialog to Publish Document showing markup - which is normally set by default if there is markup displayed in the document.

Word is not compatible with the PDF format. Word 2013 (and later) can only convert the PDF document to Word format, the content of which will depend on how the PDF was created. If you want to display PDF files, you need to open them in Adobe Reader.

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Graham Mayor - MS MVP (Word) (2002-2019)
Visit my web site for more programming tips and ready made processes www.gmayor.com

Thanks Graham,
The documents were originally created with word 2010 then I converted them to pdf to send to my lecturer for marking. The comments were added by my lecturers, but they wont open since I upgraded. Even comment balloons from earlier assignments that I could open before, wont open now that i've upgraded to office 2013. But I will try your suggestion and convert them back to word and see if I get anywhere with that. I think all my pdf documents open with adobe reader automatically.
Thanks again,
julzmacha.

I discovered that pdf documents were being opened by microsoft edge by default rather than adobe reader, so I opened them with adobe reader and was able to read comment balloons. Thankyou.

Microsoft Edge should be able to display comment balloons properly, if they are present in the PDF file. Would you mind sharing an example file that illustrates the problem?

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional