First question, downloaded using steam?

If yes, you do not have a choice steam connect to the closest server according to your geographical location the you entered in Steam.

Moving an account for 1 server to an other is NOT possible

Changing server you need to "download" the game from the website again from the correct location.

How to know an withs server you are.
1 public channel = US server (no tournaments or event happening on it at the moment)
many differend language in public channels = EU server
All Russian language in public channels = RU server

How to download the server without downloading the full 8 GB

1) If you used steam you start with point 3 for not steam go to the location of the game (original c:\games\panzar)
2) Rename Panzar to PanzarOld (DO NOT DELETE)
3) go to http://www.panzar.com
4) make sure you choose the correct location top left (Russian, Europe, US)
5) Download the launcher file install it.
6) launch it and create a NEW yes NEW account
7) if the download of the 6-8GB start Close the the launcher windows.
8) For steam jump to point 11
8) if you left the location standard copy c:\games\panzarold\bin32 to the new c:\games\panzar\bin32
9) if you left the location standard copy c:\games\panzarold\bin64 to the new c:\games\panzar\Bin64
10) if you left the location standard copy c:\games\panzarold\game to the new c:\games\panzar\game
11) for steam Copy C:\Program Files (x86)\Steam\SteamApps\common\Panzar\bin32 to the new c:\games\panzar\Bin32
12) for steam Copy C:\Program Files (x86)\Steam\SteamApps\common\Panzar\bin64 to the new c:\games\panzar\Bin64
13) for steam Copy C:\Program Files (x86)\Steam\SteamApps\common\Panzar\game to the new c:\games\panzar\game
14) go to c:\games\panzar and launch start.exe again, logon and let the rest be downloaded again.