Hey Dee, think I found one solution to your problem
In this thread
viewtopic.php?f=225&t=103740 it explains how to export MyGMs to Rosters like I'm sure you know.
What I discovered is that if you upload a team design without editing it at all, things like audio and other things that are harder to access will transfer to whatever team you load that design for, even if you export it as a regular roster afterward.
I think I can explain it better with an example.
So what I did was start a custom MyLeague with a couple teams I wanted to move, in this case the 65 Celtics and Alba Berlin. I uploaded the Celtics team design as a custom design to the 2k servers and then downloaded them for Berlin. Once I exported the roster using the trick from teh thread, things like team name, logo and audio remained saved to that team even in Quick Game and roster editing. Hopefully this helps!