diff --git a/admin/static/js/app.js b/admin/static/js/app.js
index 7916997c..176aafb3 100644
--- a/admin/static/js/app.js
+++ b/admin/static/js/app.js
@@ -464,7 +464,9 @@ angular.module("FICApp")
 		response.data.start = new Date(response.data.start);
 		response.data.end = new Date(response.data.end);
 		response.data.generation = new Date(response.data.generation);
-		$rootScope.settings = response.data;
+                if ($rootScope.settings && $rootScope.settings.activateTime instanceof Date)
+                    response.data.activateTime = $rootScope.settings.activateTime;
+	        $rootScope.settings = response.data;
 		$rootScope.recvTime(response);
 	    })
 	}
@@ -564,7 +566,8 @@ angular.module("FICApp")
         $scope.nextsettings = NextSettings.query();
         $scope.erase = false;
         $scope.editNextSettings = function(ns) {
-          $scope.activateTime = ns.date;
+          $scope.activateTime = new Date(ns.date);
+          $rootScope.settings.activateTime = $scope.activateTime;
           $scope.erase = true;
           Object.keys(ns.values).forEach(function(k) {
             $scope.config[k] = ns.values[k];
@@ -594,7 +597,7 @@ angular.module("FICApp")
 	})
 	$scope.challenge = SettingsChallenge.get();
         $scope.duration = 360;
-        $scope.activateTime = "0001-01-01T00:00:00Z";
+        $scope.activateTime = "";
         $scope.challenge.$promise.then(function(c) {
           if (c.duration)
             $scope.duration = c.duration;
@@ -656,8 +659,9 @@ angular.module("FICApp")
 	    this.config.unlockedChallengeDepth = (this.config.enableExerciceDepend?this.config.unlockedChallengeDepth:-1)
 	    this.config.disablesubmitbutton = (this.config.disabledsubmitbutton?this.config.disablesubmitbutton:'')
             var updateQuery = {};
-            if (this.activateTime && this.activateTime != '0001-01-01T00:00:00Z') {
+            if (this.activateTime && this.activateTime != '') {
                 updateQuery['t'] = this.activateTime;
+                this.activateTime = null;
             }
             if (this.erase) {
                 updateQuery['erase'] = true;
@@ -676,6 +680,7 @@ angular.module("FICApp")
                     $rootScope.settings.end = null;
                 }
 		$rootScope.settings.generation = new Date(nGen);
+                $scope.updateActivateTime();
 	    }, function(response) {
 		$scope.addToast('danger', 'An error occurs when saving settings:', response.data.errmsg);
 	    });
@@ -694,10 +699,15 @@ angular.module("FICApp")
           $rootScope.settings.activateTime = this.activateTime;
         }
         $scope.updActivateTime = function(modulo) {
+          if (modulo) {
             var ts = Math.floor((new Date(this.config.end) - $rootScope.getSrvTime().getTime() - (60000 * modulo / 2)) / (60000 * modulo)) * (60000 * modulo);
 	    var d = new Date(this.config.end) - ts;
 	    this.activateTime = new Date(d);
             this.updateActivateTime();
+          } else {
+	    this.activateTime = null;
+            this.updateActivateTime();
+          }
 	}
         $scope.reset = function(type) {
 	    var txts = {
diff --git a/admin/static/js/common.js b/admin/static/js/common.js
index 103e16a1..05574e36 100644
--- a/admin/static/js/common.js
+++ b/admin/static/js/common.js
@@ -139,7 +139,9 @@ angular.module("FICApp")
             res += Math.floor(input / 3600) + ":";
             input = input % 3600;
           }
-	  if (input >= 60) {
+	  if (res || input >= 60) {
+            if (res && Math.floor(input / 60) <= 9)
+              res += "0";
             res += Math.floor(input / 60) + "'";
             input = input % 60;
           }
diff --git a/admin/static/views/settings.html b/admin/static/views/settings.html
index f488d4ed..68dbe111 100644
--- a/admin/static/views/settings.html
+++ b/admin/static/views/settings.html
@@ -16,13 +16,13 @@
 	        <a class="dropdown-item" ng-click="updActivateTime(30)">modulo 30 minutes</a>
 	        <a class="dropdown-item" ng-click="updActivateTime(60)">modulo 60 minutes</a>
 	        <a class="dropdown-item" ng-click="updActivateTime(90)">modulo 90 minutes</a>
-	        <a class="dropdown-item" ng-click="activateTime = '0001-01-01T00:00:00Z'" ng-show="activateTimeCountDown">annuler la propagation</a>
+	        <a class="dropdown-item" ng-click="updActivateTime(null)" ng-show="activateTimeCountDown">annuler la propagation</a>
 	      </div>
 	    </div>
 	    <input type="datetime-local" class="form-control form-control-sm" id="activateTime" ng-model="activateTime" ng-change="updateActivateTime()">
           </div>
           <small ng-if="activateTimeCountDown">
-            Propagation dans : {{ activateTimeCountDown | timer }}
+            Propagation dans : {{ activateTimeCountDown | timer }}.
             Il restera : {{ timeRemaining - activateTimeCountDown | timer }}
           </small>
         </div>