How to customize the Javascript monthPicker feature?

Question

Watch the image:

When I put the cursor it shows this blue ball along with Prev, how do I customize to put before in place of Prev?

The same goes for Next

This is my Javascript file;

$(document).ready(function() {   
            $(".monthPicker").datepicker({
                dateFormat: 'MM/yy',
                changeMonth: true,
                changeYear: true,
                showButtonPanel: false,
                monthNamesShort: ['Jan', 'Fev', 'Mar', 'Abr', 'Mai', 'Jun', 'Jul', 'Ago', 'Set', 'Out', 'Nov', 'Dez'],
               // monthNames: ['1', '2', '3', '4', '5', '6', '7', '8', '9', '10', '11', '12'],

                onClose: function(dateText, inst) {
                    var month = $("#ui-datepicker-div .ui-datepicker-month :selected").val();
                    var year = $("#ui-datepicker-div .ui-datepicker-year :selected").val();
                    $(this).val($.datepicker.formatDate('mm/yy', new Date(year, month, 1)));
                }
            });

            $(".monthPicker").focus(function () {
                $(".ui-datepicker-calendar").hide();
                $("#ui-datepicker-div").position({
                    my: "center top",
                    at: "center bottom",
                    of: $(this)
                });
            });
        });

This is my file HTML;

<div class="form-group">
              <label for="inputEmail3" class="col-sm-2 control-label">Período:</label>
              <div class="row">
                  <div class="col-sm-2">
                   <input autocomplete="off" id="idPeriodoInicio" class="form-control monthPicker listar_uj" name="periodoInicio" id="periodoInicio"  placeholder="Período Inicial"> 
                  </div>
                   <div class="col-sm-2">
                    <input autocomplete="off"  id="idPeriodoFim" class="form-control monthPicker listar_uj" name="periodoFim" id="periodoFim" placeholder="Período Final">
                  </div> 
              </div>
            </div>