VM admin - settings - fourth tab (about prices)
On the left side all parameters have
<label for="show_tax">
This means that when you click on any one of them - the only changes upper checkbox.
Please can you be more specific file etc.
found and fixed, thanks
Another, the same: Vm admin, settings, third tab (templating)
In right-bottom corner - clicking on label "use jQuery for drop-downs" change the checkbox "use ajax for countries"
Sorry for possible mistakes about naming - I have russian translation of Joomla and VM.