Helper applications with Seamonkey

Hi All
My first post so I hope I am in the right place.
I am using OpenSuse Leap 42.3 with the Mate desktop and Seamonkey for my browser.
When I try to read a PDF online with Seamonkey the only option is “Eye of Gnome” which does not recognise PDF’s.
I was previously using Trueos, and by navigating to /usr/local/bin I could set the helper applications as I chose ie Okular for PDF’s.
What path would I need to use to find the applications in Opensuse?

Answered my own question
Navigate to /usr/bin open then look for Okular click open.
When you now open a PDF Okular is now shown instead of Eye of Gnome