Ah, that makes it all a lot clearer.
So summarizing:
You are running/installing 3.0.6 on a virtual machine and need to resize/set the screen resolution and are using xrandr to do that.
Primarily, seeing you have a Win10 64 bit machine I'd recommend the Beta release which has more up to date drivers and software in general.
3.0.6 is extremely Stable albeit a tad old and in some respects lacking software due to it being 32bit...so if you like it use/install it and if not, definitely try out Beta.
As to 3.0.6:
To set the screen resolution, best you use the GUI tool (arandr) for that:
Choose "applications", "preferences", "screen settings"
and in the tool choose the menu item "outputs", "default", "resolution" and choose the desired resolution among the offers.
and apply the choice, it will go into effect immediately.
I've got 3.0.0 running as GuestOs on Elive 3.6.17 Beta Host, which gives the following resolutions and the VirtualBox setting using 60Mb for the card as can be seen in the settings on the left.
