i don't have a torrent file right now but it should be as any other file
right click on the file/properties
in the first tab there is a small tool button in front of the type, press it
that will call the menu to change what app opens the file you need to edit
there should be a list with possible apps to use, put as first the one you want, if it is already at first verify that the apps is not crashed and not responding at the moment
also you can open the app you want and from there open the file
the address where the file is located, inside tmp, some apps won't work well with it, copy to your home folder or desktop could be a good idea