diff --git a/erpnext/buying/doctype/buying_settings/buying_settings.py b/erpnext/buying/doctype/buying_settings/buying_settings.py
index 91ba900873b..d4f32e7cb2b 100644
--- a/erpnext/buying/doctype/buying_settings/buying_settings.py
+++ b/erpnext/buying/doctype/buying_settings/buying_settings.py
@@ -53,6 +53,15 @@ class BuyingSettings(Document):
 		for key in ["supplier_group", "supp_master_name", "maintain_same_rate", "buying_price_list"]:
 			frappe.db.set_default(key, self.get(key, ""))
 
+		self.update_supplier_naming_settings()
+
+		if not self.bill_for_rejected_quantity_in_purchase_invoice:
+			self.set_valuation_rate_for_rejected_materials = 0
+
+	def update_supplier_naming_settings(self):
+		if not self.has_value_changed("supp_master_name"):
+			return
+
 		from erpnext.utilities.naming import set_by_naming_series
 
 		set_by_naming_series(
@@ -62,9 +71,6 @@ class BuyingSettings(Document):
 			hide_name_field=False,
 		)
 
-		if not self.bill_for_rejected_quantity_in_purchase_invoice:
-			self.set_valuation_rate_for_rejected_materials = 0
-
 	def before_save(self):
 		self.check_maintain_same_rate()
 
diff --git a/erpnext/selling/doctype/selling_settings/selling_settings.py b/erpnext/selling/doctype/selling_settings/selling_settings.py
index 66e4bf5d93a..70c57579cb2 100644
--- a/erpnext/selling/doctype/selling_settings/selling_settings.py
+++ b/erpnext/selling/doctype/selling_settings/selling_settings.py
@@ -84,14 +84,7 @@ class SellingSettings(Document):
 		]:
 			frappe.db.set_default(key, self.get(key, ""))
 
-		from erpnext.utilities.naming import set_by_naming_series
-
-		set_by_naming_series(
-			"Customer",
-			"customer_name",
-			self.get("cust_master_name") == "Naming Series",
-			hide_name_field=False,
-		)
+		self.update_customer_naming_settings()
 
 		self.validate_fallback_to_default_price_list()
 
@@ -101,6 +94,19 @@ class SellingSettings(Document):
 		if old_doc and old_doc.enable_utm != self.enable_utm:
 			toggle_utm_analytics_section(not self.enable_utm)
 
+	def update_customer_naming_settings(self):
+		if not self.has_value_changed("cust_master_name"):
+			return
+
+		from erpnext.utilities.naming import set_by_naming_series
+
+		set_by_naming_series(
+			"Customer",
+			"customer_name",
+			self.get("cust_master_name") == "Naming Series",
+			hide_name_field=False,
+		)
+
 	def validate_fallback_to_default_price_list(self):
 		if (
 			self.fallback_to_default_price_list