Samsung :-(

app/src/main/res/layout/fragment_options_notifications.xml

@@ -109,6 +109,19 @@
                     app:layout_constraintStart_toStartOf="parent"
                     app:layout_constraintTop_toBottomOf="@id/btnManage" />
 
+                <TextView
+                    android:id="@+id/tvSamsungHint"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_marginTop="6dp"
+                    android:layout_marginEnd="48dp"
+                    android:text="@string/title_advanced_notify_samsung_hint"
+                    android:textAppearance="@style/TextAppearance.AppCompat.Small"
+                    android:textStyle="italic"
+                    app:layout_constraintEnd_toEndOf="parent"
+                    app:layout_constraintStart_toStartOf="parent"
+                    app:layout_constraintTop_toBottomOf="@id/tvManageHint" />
+
                 <Button
                     android:id="@+id/btnManageDefault"
                     style="?android:attr/buttonStyleSmall"
@@ -119,7 +132,7 @@
                     android:drawablePadding="6dp"
                     android:text="@string/title_advanced_notifications_default"
                     app:layout_constraintStart_toStartOf="parent"
-                    app:layout_constraintTop_toBottomOf="@id/tvManageHint" />
+                    app:layout_constraintTop_toBottomOf="@id/tvSamsungHint" />
 
                 <ImageView
                     android:id="@+id/ivChannelDefault"

app/src/main/res/values/strings.xml

@@ -1154,6 +1154,7 @@
     <string name="title_advanced_notify_car_hint">Connected means something is being projected, such as a map for navigation</string>
     <string name="title_advanced_notify_remove_hint">New message notifications will always be removed on being swiped away and on marking messages read</string>
     <string name="title_advanced_notify_manage_hint">Tap on the channel name to set the channel properties</string>
+    <string name="title_advanced_notify_samsung_hint">To manage notification channels, you may need to enable this Android setting: Notification, Advanced settings, Manage notification categories for each app</string>
     <string name="title_advanced_notify_manage_default_hint">To set the default sound, etc.</string>
     <string name="title_advanced_notify_manage_service_hint">To disable the \'monitoring\' notification</string>
     <string name="title_advanced_notify_separate_hint">How do I configure notifications for accounts, folders and senders?</string>