how you can change Magento Core API settings?

To change Magento Core API settings, you have to
  • Go to Admin menu, choose System -->Configuration
  • Select Magento Core API on the left side of the Configuration Panel, under Services
  • Tap on to expand the General Settings section and you can
  • Type the name of the Default Response Charset that you want to use
  • Determine the Client Session Timeout in seconds
  • Click the Save Config button when complete