Pressing the «Settings» button will take you to the Game Settings screen:

Game Settings screen
Here you'll find the following settings:
Graphic settings:
«Autodetect» - this button allows you to let the game decide for itself what are the best settings considering your PC parameters
«Presets» - Complex graphics settings.
«Static objects textures» - Set the quality of static objects texturing on the battlefield. Setting this to the minimum level could increase game performance during battles.
«Terrain Geometry» - Set the quality of terrain elements on the battlefield. Setting this to the minimum level could increase game performance during battles.
«Terrain textures» - Set the quality of terrain texturing on the battlefield. Setting this to the minimum level could increase game performance during battles.
«Units textures» - Set the quality of unit texture. Setting this to the minimum level could increase game performance during battles.
«Shaders» - Set the quality of shaders. Setting this to the minimum level could increase game performance during battles.
«Shadows» - Set the overall quality of shadows. Setting this to the minimum level could increase game performance during battles.
«Enable FX» - Enable or disable rain, fog etc effects on map.
«Enable DOF» - Enable or disable DOF post-effect. Disabling this post-effect could increase game performance during battles.
«Grass density» - Choose the level of detail for grass on the battlefield. Setting this to the minimum level could increase game performance during battles.
Sound settings:
This menu allows you to control the levels of sounds and music in the game, or disable them altogether.
Redefine keys:
This menu allows you to redefine hot-keys for different actions in the game.
Game Settings:
This menu allows you to switch interface hints on or off, and define mouse sensitivity, camera movement and rotation speed.