Source: http://worldoftanks.ru/ru/news/1/810_settings_graphics/

Hello everyone,

this is an important message for all of you about a nasty surprise, waiting for you in patch 8.10.

In patch 8.10, ALL client graphic settings will reset! This exactly happened in the test client. Basically, the game runs an autodetection procedure to determine, what settings are “good” for your computer and changes them. As you can imagine, this can screw up the settings you were used to, so, in order to avoid all the confusion of “how did I have it before”, what you should do is:

Start the client, go to your graphic settings panel (under the settings window) and press “printscreen” key to create a screenshot. When putting your settings back together, you can refer to that screenshot (saved in the world_of_tanks/screenshots/ folder) to see how you had it before. For people like me, who have not touched the graphic settings for quite a while, this is quite important.