How to handle google play games service on Sceneswitch?

How do you Handle Leaderboard and achievements on Scene Switch?

Is your PlayGames class static or how to prevent the user from logging off on Scene switch?

Currently I handle all in one Scene and when the user clicks on Leaderboard or Achievements the score and achievements gets updated, but that is not a good Solution because the User gets logged in every time the MainMenu Scene is loaded.