diff --git a/Blazor/Blazor/Models/AdministratorModel.cs b/Blazor/Blazor/Models/AdministratorModel.cs
index 91d1dd6..af3ca37 100644
--- a/Blazor/Blazor/Models/AdministratorModel.cs
+++ b/Blazor/Blazor/Models/AdministratorModel.cs
@@ -11,7 +11,8 @@ public class AdministratorModel
     public int Id { get; set; }
 
     [Required(ErrorMessage = "Username is required")]
-    [StringLength(50, ErrorMessage = "Username is too long.")]
+    [RegularExpression(@"^[a-zA-Z0-9]+$", ErrorMessage = "La chaîne doit être composée uniquement de lettres et de chiffres, sans espaces.")]
+    [StringLength(20, ErrorMessage = "{0} length must be between {2} and {1}.", MinimumLength = 3)]
     public string Username { get; set; }
 
     [Required(ErrorMessage = "Password is required")]
diff --git a/Blazor/Blazor/Models/PlayerModel.cs b/Blazor/Blazor/Models/PlayerModel.cs
index a8da40a..d202d12 100644
--- a/Blazor/Blazor/Models/PlayerModel.cs
+++ b/Blazor/Blazor/Models/PlayerModel.cs
@@ -10,7 +10,8 @@ public class PlayerModel
     public int Id { get; set; }
 
     [Required(ErrorMessage = "Nickname is required")]
-    [StringLength(50, ErrorMessage = "Nickname is too long.")]
+    [RegularExpression(@"^[a-zA-Z0-9]+$", ErrorMessage = "La chaîne doit être composée uniquement de lettres et de chiffres, sans espaces.")]
+    [StringLength(20, ErrorMessage = "{0} length must be between {2} and {1}.", MinimumLength = 3)]
     public string Nickname { get; set; }
 
     [Required(ErrorMessage = "Password is required")]
diff --git a/Blazor/Blazor/Pages/Questions/AddQuestion.razor b/Blazor/Blazor/Pages/Questions/AddQuestion.razor
index 5dd9421..767b518 100644
--- a/Blazor/Blazor/Pages/Questions/AddQuestion.razor
+++ b/Blazor/Blazor/Pages/Questions/AddQuestion.razor
@@ -38,7 +38,7 @@
                 <InputText id="@($"answer{answerModel.Id}")" @bind-Value="answerModel.Content" />
             </label>
             <label for="@($"checkbox{checkbox.Id}")">
-                <InputCheckbox id="@($"checkbox{checkbox.Id}")" @bind-Value="checkbox.IsCorrect" /> Correcte
+                <input type="radio" name="radio" id="@($"checkbox{checkbox.Id}")" checked="@checkbox.IsCorrect" @onchange="() => SetCorrectAnswer(checkbox.Id)" /> @Localizer["Correct"]
             </label>
         </p>
     }
diff --git a/Blazor/Blazor/Pages/Questions/AddQuestion.razor.cs b/Blazor/Blazor/Pages/Questions/AddQuestion.razor.cs
index 638269b..4628617 100644
--- a/Blazor/Blazor/Pages/Questions/AddQuestion.razor.cs
+++ b/Blazor/Blazor/Pages/Questions/AddQuestion.razor.cs
@@ -58,6 +58,11 @@ namespace Blazor.Pages.Questions
                 checkboxs.Add(new Checkbox(i));
             }
         }
+
+        private void SetCorrectAnswer(int checkboxId)
+        {
+            questionModel.IdAnswerGood = checkboxId;
+        }
         private async Task HandleValidSubmit()
         {
             if (questionModel != null)
@@ -70,15 +75,9 @@ namespace Blazor.Pages.Questions
                     var answercontent = $"answerContent{answerModel.Id + 1}";
                     formData.Add(new KeyValuePair<string, string>(answercontent, answerModel.Content));
                 }
-                foreach (var checkbox in checkboxs)
-                {
-                    if (checkbox.IsCorrect != false)
-                    {
-                        var idgood = checkbox.Id + 1;
-                        IdAgood = idgood;
-                        formData.Add(new KeyValuePair<string, string>("idanswergood", idgood.ToString()));
-                    }
-                }
+                var idGood = questionModel.IdAnswerGood + 1;
+                formData.Add(new KeyValuePair<string, string>("idanswergood", idGood.ToString()));
+                
              
                 var formContent = new FormUrlEncodedContent(formData);
 
diff --git a/Blazor/Blazor/Pages/Questions/EditQuestion.razor b/Blazor/Blazor/Pages/Questions/EditQuestion.razor
index 834ae28..929b287 100644
--- a/Blazor/Blazor/Pages/Questions/EditQuestion.razor
+++ b/Blazor/Blazor/Pages/Questions/EditQuestion.razor
@@ -38,7 +38,7 @@
                 <InputText id="@($"answer{answer.Id}")" @bind-Value="answer.Content" />
             </label>
             <label for="@($"checkbox{checkbox.Id}")">
-                <InputCheckbox id="@($"checkbox{checkbox.Id}")" @bind-Value="checkbox.IsCorrect" />  @Localizer["Correct"]
+                <input type="radio" name="radio" id="@($"checkbox{checkbox.Id}")" checked="@checkbox.IsCorrect" @onchange="() => SetCorrectAnswer(checkbox.Id)" />  @Localizer["Correct"]
             </label>
         </p>
     }
diff --git a/Blazor/Blazor/Pages/Questions/EditQuestion.razor.cs b/Blazor/Blazor/Pages/Questions/EditQuestion.razor.cs
index 3f993bc..6fdad16 100644
--- a/Blazor/Blazor/Pages/Questions/EditQuestion.razor.cs
+++ b/Blazor/Blazor/Pages/Questions/EditQuestion.razor.cs
@@ -82,6 +82,14 @@ namespace Blazor.Pages.Questions
             OldQuestionIdChapter = question.IdChapter;
             OldIdAnswerGood = question.IdAnswerGood;
         }
+
+        private void SetCorrectAnswer(int checkboxId)
+        {
+            Console.WriteLine($"SetCorrectAnswer called with checkboxId: {checkboxId}");
+            questionModel.IdAnswerGood = checkboxId;
+        }
+
+
         private async Task HandleValidSubmit()
         {
 
@@ -94,14 +102,8 @@ namespace Blazor.Pages.Questions
                 var answercontent = $"answerContent{index + 1}";
                 formData.Add(new KeyValuePair<string, string>(answercontent, answer.Content));
             }
-            foreach (var checkbox in checkboxs)
-            {
-                if (checkbox.IsCorrect == true)
-                {
-                    IdAgood = checkbox.Id;
-        formData.Add(new KeyValuePair<string, string>("idanswergood", checkbox.Id.ToString()));
-                }
-            }
+
+            formData.Add(new KeyValuePair<string, string>("idanswergood", question.IdAnswerGood.ToString()));
 
             var formContent = new FormUrlEncodedContent(formData);