OK, 949k miles on the books, a master of the pmUA world and totally befuddled by the new order. Can someone guide me....

LAX-HNL in YN
HNL-LAX in Y

What is YN??

I am offered a 10,000 mile upgrade outbound (in YN) but not back. Why??
Do I need to do anything to get into the UDU queue?? 767 both ways, KVS shows
J9 JN9 C9 R0 RN0 out and back

embarrassed to be asking for an upgrade primer at this point, but IT IS TOTALLY NOT CLEAR.