open links in okular with Firefox

Problem
You have a PDF that contains links. You click on a link but it opens in a strange browser (Konqueror?). How to open links with Firefox?

Solution

1. Run the command “kcmshell4 filetypes“. File Associations – KDE Control Module will open.
2. Search for html and select the file type text/html.
3. Move the application name you want to be a default for html in the “Application Preference Order” to the top.

I copied this solution from here. Credits go to djhurio.