Form action in modal

The buttons must go inside the form something like:

    <form action="{{url('/orderUpdate')}}/{{$o->idOrder}}" method="POST">
      <div class="col-sm-10">
         <select class="form-control" name="Status">
            <option value="1">Pendiente</option>
            <option value="2">En Proceso</option>
            <option value="3">Finalizada</option>
         </select>
         <button type="button" class="btn btn-default" data-dismiss="modal">Cerrar</button>
        <button type="submit" class="btn btn-primary" data-dismiss="modal">Actualizar</button>
       </div>  
    </form>

Also you had an error in the form the div with the class col-sm-10 is not closing.

Basically you had a bad order in your code, div without closing and the button that sends the data to the controller was out of form , well the code would be this:

<div class="modal fade" id="modalUpdate{{$o->idOrder}}" tabindex="-1" role="dialog" aria-labelledby="myModalLabel">
    <div class="modal-dialog" role="document">
        <div class="modal-content">
            <div class="modal-header">
                <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
                <h4 class="modal-title" id="myModalLabel">¿Deseas Actulizar la orden?</h4>
            </div>
            <form action="{{url('/orderUpdate')}}/{{$o->idOrder}}" method="POST">
                <div class="modal-body">
                    <div class="form-group">

                        <div class="col-sm-10">
                            <select class="form-control" name="Status">
                              <option value="1">Pendiente</option>
                              <option value="2">En Proceso</option>
                              <option value="3">Finalizada</option>
                           </select>

                        </div>
                    </div>
                </div>
                <div class="modal-footer">
                    <button type="button" class="btn btn-default" data-dismiss="modal">Cerrar</button>
                    <button type="submit" class="btn btn-primary" data-dismiss="modal">Actualizar</button>
                </div>
            </form>
        </div>
    </div>
</div>