Set Acrobat as default

Hi,

I use Acrobat X on WIndows 10 on a Surface Pro 2.

Acrobat Reader has set itself as a default program for pdfs and I am nt able to change it Adobe Acrobat,

When I open an email attachment (in outlook)  it will open with Acrobat Reader.

I went with the steps in Adobe Acrobat as you suggested , with Edit, etc, and it did not change the default to Adobe Acrobat but rather to MS Edge browser...

initially in Edit> Preferences> General> when I clicked on Adobe Acrobat to be my default PDF handler  on it started doing something - a green bar appeared but it gave a message that it is not able to do it and will set it to explorer instead. I tried again and it would not finish the action but just abort... several times the same ... s now it is even worse - because the PDF attachements are now marked as HTM not PDF ...

any ideas how to fix it?