minor fix

app/main.py

@@ -2394,7 +2394,9 @@ class AppWindow(FrontWindow):
         self.input_text_changed('')
         self.amount_text_changed('0')
         self.clear_sign()
+        change = self.field_change.text()
         self.clear_right_panel()
+        self.field_change.setText(change.replace(',', ''))
         self.show_right_panel(True)
         self.payment_ctx = {}
         self.table_sale_lines.setEnabled(True)