Especially I need to hint the button for unregistered users.
Thanks for your help.
I suppose you want to "hide" the button for unregistered users.
See here: http://forum.virtuemart.net/index.php?topic=91385.msg300478#msg300478 (http://forum.virtuemart.net/index.php?topic=91385.msg300478#msg300478)
Oh for sure i want to hide. :) Sorry.
The link you have posted is about the same problem and unfortunately not solved. :'(
...but it contains two hints how to solve it ;)
Also you can set up the cart so that unregistered users are forced to register first before they are able to click on "confirm order".