For 2017, these should be the instructions: https://helpx.adobe.com/acrobat/using/edit-text-pdfs.html
We used to have Adobe Pro where I worked and one of the "updates" took away all ability to edit the text. It could be the company went cheap, I couldn't find edit text anywhere. But, there's a work around.
Save the doc as PDF. Then import the PDF into MS Word (I think most word processors do this now). It won't be perfect, but you should be able to add text, get it more or less lined up, and then save it as PDF again. Be warned, you will curse a lot.