Preventing repetition of a Form

Dear list -

I have a program [*pseudo code*]:

        if(!isset($_REQUEST["welcome_already_seen"]))
        {
             initialize variables
        }

           $errors_array = array();
             if($_REQUEST["welcome_already_seen"]== "already_seen")
             {
             check_data();
                    if(count($errors_array) != 0)
                    {
                     show_errors();
                     show_welcome();
                 }
                 else
                 {
                     show_welcome();
                 }
             }
             if(!isset($_REQUEST["welcome_already_seen"]))
                   show_welcome();

                             switch ( $_POST['next_step'] )
                             {

                                 case "step5":
                                 {
                                     do something
                                     form
                                     next_step = step8;
                                    /form
                                 }

                                 case "step10":
                                 {
                                     do something
                                     form
                                     next_step = step5;
                                      /form
                                }

                             etc...etc
                             } //end switch

             function show_welcome()
             {
                        do something
                         form
                         next_step = step10;
                         /form
               }

The  show_welcome() persists in each step.

How do I make it go away after step10?

Thanks.

Ethan