Removing password requirement each time I open the document

[82011362]

I purchased a book in pdf.  After you download the pdf you are given a password to open it.  No problem.  But everytime I want to open it I have to keep re-entering the password.  Is there a way to stop this?

I tried going into Preferences to chnage the settings to "No security".  When doing so another password bos pops up promting for a password.  I enter the password the author gave to me, but it says it's an invalid password.  So there is one password to open the pdf but another to change the security settings?

Adobe Acrobat Pro DC.

[Karl Heinz Kremer]

There are two passwords that can be associated with a PDF file: An "open password", which is what you have to enter every time you try to open the document, and an "owner password", which is the password that the document author applied in order to prevent you from removing the open password. There is no way around this, unless you can convince the author to give you a version of the document without the open password.