Variable usage in livecycle ES4

Good morning everyone,

I'm trying to use the variables today and assigning values using code.

Right now I created a variable under the variable section called "formNb".

I want to assign a value to that variable on initialize by using the response approach.

so far it works except that the value isn't stored permanently in the variable, every time I restart the form, I get to re-enter the value.

here's my code,

if (formNb.value==null || formNb.value==""){

//ask user to forward the 4 digit form #XXXX

var tmptest1=xfa.host.response("What is the 4 digit form # for this new form? :");

formNb.value=tmptest1 + "e";

}

I know that when you go thru the forms properties-> variables and enter a value there, it retains it for ever.

Can I mimic this behavior via code so that the value passed on to the variable will remain for ever?

Thank you so much again