Undo display sync - but how?

[naish1]

Hey,

 

after having installed SL on my 10v I tried to use an external Monitor (1920x1080). In general it worked but unfortunately I activated the option "sync displays". As soon as this option was activated both displays only showed stripes in various colours. By detaching the vga cable I can use the display of the 10v again, but I don´t find any way to use the external display again.

 

Do you have an idea what I can try to undo the option "sync displays"???

 

Thanks for your help!!