Do you mean updating game mode options while you’re already running the game mode in the level you want, or before loading the level?
If before loading the new level / creating a new session, one thing you can do is use Option Strings and parse them to set values accordingly. Or pass the data around in something more persistent like in the game instance. Those are two things I have done.
As for the PostLogin thing you have not working, what’s going wrong? I assume you override PostLogin or use the Blueprints event and check whether bGameLogicActive is true or false?