Who can approve invoices
Anybody can do it who has been set as a responsible person in the approval policies. The invoice will automatically show up for the person who is responsible for it.
How to approve invoices
Invoices need to be approved or rejected for the process to come to an end.
Click on "Invoices" > "Needs Approval"
Choose an Invoice that you want to approve
Check if the Invoice details are correct
Approve or reject the invoice