Setting Default PDF App

On your own computer:

Start menu (bottom-left corner) --> search for and click on Default Apps --> Choose default apps by file type (blue link) --> scroll way down the list to .PDF and click the currently-set program (e.g. Microsoft Edge) --> change to the preferred Adobe app (whether you have Reader or Acrobat, as shown below).

Alternatively, or on the terminal server (remote.ffl.net) where you cannot access Default Apps:

Right-click a PDF file --> Properties --> Change... --> select the preferred Adobe app and it should set it as default for all documents of the same file type.