Here are some instructions for changing the default program.
http://www.howtogeek.com/237512/how-to-change-the-default-pdf-reader-in-windows-10/
Here are the highlights:
1. Right click on the PDF and choose Open with...
2. Click on "Choose another app"
3. Find Acrobat or Reader, BE SURE TO CLICK THE CHECKBOX "ALWAYS USE..."
Your screen may not look exactly like this, but the process will be similar.