diff --git a/samples/query_external_sheets_permanent_table.py b/samples/query_external_sheets_permanent_table.py
index 915e9acc3..31143d1b0 100644
--- a/samples/query_external_sheets_permanent_table.py
+++ b/samples/query_external_sheets_permanent_table.py
@@ -21,6 +21,12 @@ def query_external_sheets_permanent_table(dataset_id):
 
     # Create credentials with Drive & BigQuery API scopes.
     # Both APIs must be enabled for your project before running this code.
+    #
+    # If you are using credentials from gcloud, you must authorize the
+    # application first with the following command:
+    #
+    # gcloud auth application-default login \
+    #   --scopes=https://www.googleapis.com/auth/drive,https://www.googleapis.com/auth/cloud-platform
     credentials, project = google.auth.default(
         scopes=[
             "https://www.googleapis.com/auth/drive",
diff --git a/samples/query_external_sheets_temporary_table.py b/samples/query_external_sheets_temporary_table.py
index 1b70e9531..a9d58e388 100644
--- a/samples/query_external_sheets_temporary_table.py
+++ b/samples/query_external_sheets_temporary_table.py
@@ -22,10 +22,16 @@ def query_external_sheets_temporary_table():
 
     # Create credentials with Drive & BigQuery API scopes.
     # Both APIs must be enabled for your project before running this code.
+    #
+    # If you are using credentials from gcloud, you must authorize the
+    # application first with the following command:
+    #
+    # gcloud auth application-default login \
+    #   --scopes=https://www.googleapis.com/auth/drive,https://www.googleapis.com/auth/cloud-platform
     credentials, project = google.auth.default(
         scopes=[
             "https://www.googleapis.com/auth/drive",
-            "https://www.googleapis.com/auth/bigquery",
+            "https://www.googleapis.com/auth/cloud-platform",
         ]
     )