cubietruck, armbian and screen resolution

[geka]

hello

I am new to the forum
My problem:

      how to change the screen resolution when I'm on the output vga?

the only proposed resolution is 1920X1080

 

board : cubietruck

 

 

linux : Armbian_4.5_Cubietruck_Debian_jessie_3.4.109-legacy

 

screen : VGA output, 1280X1024

 

Desktop environment : XFCE 4.10

 

 

Thanks for your help