Problems with var on different clients

I need your help
I create a multiplayer game about tanks
I need to create a variable (which later will display the total number of victories in the HUD, each player, of course, your score wins), which will retain its value when changing levels

  1. It will be stored in the Game Instance, as there are variables are not reset when you change level
  2. How do I arrange for each player score his victories? And to keep it even when you change levels: here I was trying somehow to write your own, or take a Player ID and write to an array, but did not do it properly and I did not work (and it is a major problem, help me, please)
  3. Well, the conclusion in the HUD for each client (when a server is listen)
    Thank you, I will wait for the answer!

read this:
http://cedric.bnslv.de/Downloads/UE4_Network_Compendium_by_Cedric_eXi_Neukirchen.pdf

Also do not use listen server until you know how multiplayer works. Listen server is server and client in single process, many things work locally, then you try remote clients and your game does not work, it easily confuses. Start with dedicated server and 2 remote clients.