Login into your Xero account, click Settings and click "Disconnect from Xero".
Clicking the EzzyBills top menu to go back to the main window. Click the browser refresh button if you do not see the Connect to Xero buttton.
Click "Connect to Xero" button to authorise a connection to another Xero company.
Click the "Refresh GL" button in EzzyBills User Settings (so the cache gets cleared).