This is a 100% custom modification and unfortunately we don't provide free support or step-by-step instructions for custom coding modifications.
You may purchase premium support:
www.flexiblewebdesign.com/premium-support
and let us take care this modification for you directly on your website though.
TIP:
That form is generated by this PHP file:
/templates/flexible_coolmart/html/com_virtuemart/user/edit_address_userfields.php
You may try this CSS rule:
form.FORM_CLASS_NAME input,
form.FORM_CLASS_NAME select {
width:300px !important;
}
* replace the
FORM_CLASS_NAME depends on which form you want to apply this rule.
So, the "SELECT" box and the "INPUT" fields will all have 300px width.
Regards.
Support