Yes...you would write a 2 scripts that sets a GPRM value according to which button the user has selected. When you return you would go to another script that "tests" which value is currently valid and highlight the appropriate button. This is just one way...there are endless ways to write scripts
Stereo:
1.Set GPRM 0=0
5.1:
1.Set GPRM0=1
On the return to the audio menu:
1. If GPRM 0=0 highlight button Stereo
2. If GPRM 0=1 highlight button 5.1
this is not exact scripting verbiage but kind of gives you an idea anways
here's a good site to learn scripting:
http://www.dvdstudiopro.co.uk/tutorials/