He is not loading multiple instances if he points every track at the same synth, which I think he did.

He was just doing it manually, instead of having the synth load automatically.

Remember to save the song once after assigning the default synth.
I would set up default DXi as John mentioned, save song, close RB and reopen to see if the settings 'stick'.

I do not work here, but the benefits are still awesome
Make your sound your own!