diff --git a/apps/m3u/api_views.py b/apps/m3u/api_views.py
index 6176a0ca..daac92b1 100644
--- a/apps/m3u/api_views.py
+++ b/apps/m3u/api_views.py
@@ -51,7 +51,15 @@ class M3UAccountViewSet(viewsets.ModelViewSet):
             # Add file_path to the request data so it's available during creation
             request.data._mutable = True  # Allow modification of the request data
             request.data['file_path'] = file_path  # Include the file path if a file was uploaded
-            request.data.pop('server_url')
+            
+            # Handle the user_agent field - convert "null" string to None
+            if 'user_agent' in request.data and request.data['user_agent'] == 'null':
+                request.data['user_agent'] = None
+                
+            # Handle server_url appropriately
+            if 'server_url' in request.data and not request.data['server_url']:
+                request.data.pop('server_url')
+                
             request.data._mutable = False  # Make the request data immutable again
 
         # Now call super().create() to create the instance
@@ -82,16 +90,24 @@ class M3UAccountViewSet(viewsets.ModelViewSet):
             # Add file_path to the request data so it's available during creation
             request.data._mutable = True  # Allow modification of the request data
             request.data['file_path'] = file_path  # Include the file path if a file was uploaded
-            request.data.pop('server_url')
+            
+            # Handle the user_agent field - convert "null" string to None
+            if 'user_agent' in request.data and request.data['user_agent'] == 'null':
+                request.data['user_agent'] = None
+                
+            # Handle server_url appropriately
+            if 'server_url' in request.data and not request.data['server_url']:
+                request.data.pop('server_url')
+                
             request.data._mutable = False  # Make the request data immutable again
 
             if instance.file_path and os.path.exists(instance.file_path):
                 os.remove(instance.file_path)
 
-        # Now call super().create() to create the instance
+        # Now call super().update() to update the instance
         response = super().update(request, *args, **kwargs)
 
-        # After the instance is created, return the response
+        # After the instance is updated, return the response
         return response
 
     def partial_update(self, request, *args, **kwargs):
diff --git a/frontend/src/components/forms/M3U.jsx b/frontend/src/components/forms/M3U.jsx
index 8e8fd932..9affa984 100644
--- a/frontend/src/components/forms/M3U.jsx
+++ b/frontend/src/components/forms/M3U.jsx
@@ -307,7 +307,7 @@ const M3U = ({
               description="User-Agent header to use when accessing this M3U source"
               {...form.getInputProps('user_agent')}
               key={form.key('user_agent')}
-              data={[{ value: '0', label: '(use default)' }].concat(
+              data={[{ value: '0', label: '(Use Default)' }].concat(
                 userAgents.map((ua) => ({
                   label: ua.name,
                   value: `${ua.id}`,