you'll need something like adobe acrobat in order to do that. See this link, it is for excel but the principle should be the same - it makes use of a free pdf editor
Depends whether you are trying to protect an existing PDF or a new PDF.
The free Acrobat Reader will not password protect existing PDFs ... unless you pay a monthly fee ($13-15 per month!)
For a newly created PDF:
It can't be done from Access
However, it can be done from Word.
Before saving a Word doc as a PDF, click Options.
Then select 'Encrypt this document with a password'
Enter a password between 6 and 32 characters.
Job done!
This method does provide an indirect way of protecting existing PDFs
Open the PDF in Word (2016).
Now Save As ... and enter a new file name.
Add a password as before.
NOTE: Opening a PDF in Word 2016 is usually fine but may not give perfect results if the document is very complex.
just crossed my mind.
what does the OP means when she/he
said Password Protect.
most password protected pdfs can
be opened. but only their contents
are protected from copying and alteration.
they can be printed too.
none did i see a pop-up dialog asking
for a password.