Its clunky but in a different way to my original post. If I go to options 'midi/audio driver set up' it shows me the default synth. clicking on it takes me to the plugins where i can change the synth. but when i return to the midi/audio drivers dialogue the default synth hasn't changed which is why I said I had to do it twice.

however, close the dialogue panel and reopen and the changed synth is shown.

its the dialogue that's not refreshing. but i'd still like to choose the default synth from the midi/audio drivers panel without going to plugins.

will post in wish list