radio button will trigger the form submit

Hi,
Our application has a web forms page, which has a radio button, click on it will present different views. This used to work fine for 6 years; recently we have a new request: modify this page so all input values will be submitted to a 3rd party company's url.
The same code this 3rd party company provided, is to put this line of code in Page_Load, in code behind
form1.action = (string)Session["formUrl"]; // which they pass us the Session["formUrl"]
Now, what we did first is to put this line of code in Page_Load; what happens is: whenever the radio button was clicked, it will go to this url directly - of course this is wrong;
Then, we moved this line of code out of Page_Load, and added it to the function tied to the event of user clicking the "Submit" button; now, the radio button "switching view" works, however, whenever the user clicks the "Submit" button, it stays on th ...