All I want is to set a scope change before opening the modal 
so I put ng-click="change = false;mode = 'edit';" in the edit button 
The wrong scenario is when I click on edit the scope should be false
but if I change it to true by pressing the change button and then I close the modal and I click again on edit to open the modal again you can see that the scope is still true while it should be reset back to false
Any explanations ?
I made this exemple in Plunker ,
Here's the code:
<!DOCTYPE html>
<html ng-app="app">
<head>
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
  <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.4/angular.min.js"></script>
  <script>
    var app = angular.module('app', []);
    app.controller('MainCtrl', function($scope) {
    });
  </script>
</head>
<body ng-controller="MainCtrl">
  <button type="button" class="btn btn-info btn-lg" data-toggle="modal" data-target="#myModal" ng-click="mode = 'add'">Add</button>
  <button type="button" class="btn btn-info btn-lg" data-toggle="modal" data-target="#myModal" ng-click="change = false;mode = 'edit';">Edit</button>
  <!-- Modal -->
  <div class="modal fade" id="myModal" role="dialog" ng-switch on="mode">
    <div class="modal-dialog">
      <!-- Modal content-->
      <div class="modal-content">
        <div class="modal-header">
          <button type="button" class="close" data-dismiss="modal">×</button>
          <h4 class="modal-title" ng-switch-when="add">Add</h4>
          <h4 class="modal-title" ng-switch-when="edit">Edit</h4>
        </div>
        <div class="modal-body">
          <p>{{mode}} </p>
          <button type="button" class="btn btn-default" ng-click="change = false" ng-show="change">Change</button>
          <button type="button" class="btn btn-default" ng-click="change = true" ng-show="!change">Revert</button>
          <p>{{change}} </p>
        </div>
        <div class="modal-footer">
          <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
        </div>
      </div>
    </div>
  </div>
</body>
</html> 
     
    