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