Outlook 2016 keeps changing Adobe pdf's into Edge Format

I am using Adobe Acrobat XI

I am using Outlook 2016 on a Windows 10 machine.  I have gone into Settings: Default Apps: Choose default app by file type: pdf set to Adobe Acrobat.

I have attempted to change the registry in a couple of places to keep Edge from changing the pdf's from adobe into Edge format.

When the pdfs are on my desktop or within the computer, the are  Adobe, and tend to stay that way.  When I copy and paste them into Outlook to send as an email, they show up in the email as and Edge file.

In addition, when I receive an email that has a Adobe pdf attachment, it is displayed as Edge file.   Once I copy that attachment from Outlook onto my desktop, it reverts back to an Adobe file.

I do not want Outlook to display the pdf's as an Edge File.  I want them to be displayed, and opened with Adobe.

Any help would be appreciated.

Thank you!