I am so sorry that I am not good at German but a student learning German. I meet this problem too, and there is no option to change the frequency, but there is a trick, which might realize what you wanna. First, exit full screen mode by clicking alt+enter, second, change the resolution more that 640*480 in your VPC environment. Finally, press alt+enter again into full screen mode, then the frequency in VPC is the identical as your host OS enviorment. P.S. You'd better install the VPC utilities before you do things before...
