Links to local PDFs—how to disable the warning

Unlike the user who raised this issue:

Disabling security for locally linked PDF’s

I find this warning a nuisance for my clients, who are accessing over 100 different PDFs and constantly have to respond to this dialog box

I have studied the forums and only found discussion about accessing PDFs on the internet. Apart from the post mentioned above.

How can I disable this feature in Acrobat Reader?

I tried going to Edit > Preferences > Trust Manager as mentioned but it was all about the Internet, not local files

I then discovered Edit > Preferences > Security (Enhanced) and added the path of the folder containing the PDFs.  I restarted Acrobat Reader .  The messages stopped appearing

BUT then I closed Acrobat Reader and started it again. I opened a document from a copy of the PDFs that is in a different location, away from the path that I entered.  The security warnings continued not to appear!

Can someone please explain the rules to me?  How it works? I have to put a concise explanation for clients to be able to get rid of these messages.  Acrobat Reader is still behaving in mysterious ways.