When publishing invoices to Xero there is the option of approving invoices there in one of 3 ways:
Draft
Awaiting Approval
Awaiting Payment
To select the format simply go to the Integrations page (under Company Settings) and select the option for both Purchase and Sales invoices from the drop down menus:
On this page you can also select:
To disconnect from Xero
Re-Sync Xero Data (if major changes are made in Xero, this will pull through the updated data from Xero)
Allow Duplicate invoices to be approved to Xero (over-ruling our duplicate check)
Turn on/off billable expenses feature (tracking by customer)