Passing variables

Hello,
I have a problem with passing variables from one Form to another.

I have for example Form1 and Form2.

Form1:
Global variable:

MyForm2 :: Form :: Form2
pCustNo :: Text :: 30


On this form I have button OnPush():

CLEAR(MyForm2);
pCustNo := Rec."No."; //CODE to Text
MyForm2.SetCustomer(pCustNo);
MyForm2.RUN;


Form2

Global variables:

gboAttributeToBeSet :: Text :: 30

Function:
SetCustomer(VAR pCustNo : Text[30])
gboAttributeToBeSet := pCustNo;


The problem begins with:
When I compile Form2. Close everything. Then Open Form1 and push the button, it passes the variable fine.

But when I close Form2 and go to another record in Form 1 and push the button, in Form2 is in the Textbox still the first value.

The only action which will pass the value ok is to compile the Form2. Then it passes the value fine but again the value remains there.

Im newbie and I looked everywhere. Can you please help me?
Thank you.