Many of my files have the 'Title' and 'author' as someone else as files have been edited and changed over time. These details are greyed out when I go to 'properties' so I can not put my info in for 'Title' and 'Author'.
Not possible with Acrobat Reader.
You can change document propertied Acrobat Help | PDF properties and metadata using Acrobat application Download Adobe Acrobat free trial | Acrobat Pro DC. However its not possible using free Reader application.
Thanks to all who answered. I understand that I can not edit the PDF details but I did work out how to change the details in the original document and those details did transfer to the PDF conversion of the doc.
Thanks all for helping me understand how these things work.
Happy New Year and all the best for 2016.
There are many online PDF Editors that let you change metadata: https://www.sejda.com/edit-pdf-metadata is one I found through ecosia.com <-- what I use instead of Googling as it plants trees rather than making themselves richer. * Note: I have not tried Sejda's service.