cannot change default VAT settings

i tried to change the VAT tax setting, to my country VAT, which is 24%.But in VirtueMart control panel when i try to change tax, it will always keep the default, which is "without VAT:0%".
How can i change this?
I have searched also the VirtueMart forums and no response.
Please help me.
Thank you.

Please make sure that you have enabled Virtual TAX if your products has 0 for dimensions and weight.

it is ok now but i want to display the net price without tax in the products page.
Now it displays the price with taxes.
Can we do that?

Please check VM configuration carefully. You have all options there.

I checked and double-checked and the only thing that i can do is to display the message "including 24% tax" after the price.

i solved it was in shoper section for the groups an checkbox.
thank you.