You need to View an Invoices to be able to change the Invoice Status or charge for it.
Cancelled:
An Unpaid invoice can be Cancelled. That means the amount is not outstanding and client cannot see it.
Draft:
A Draft Invoice is not visible to the client. It can be Deleted or marked a Unpaid or Paid.
You can choose a date range and the Draft Invoice will scan the schedule for un-invoiced items for this client.
Non-billable:
You can set the status of an Unpaid Invoice to Uncollectable. Invoices that are uncollectible can be Cancelled or Deleted.
Paid:
You can Charge a creditord to pay for the Invoice or mark it as Paid specifying whether the payment was Cash, Check, e-Transfer.
Partial:
When paying for an Invoice (or marking it as Paid) you can enter an amount that is lower than the total Invoice amount. An Invoice that is marked as Paid with a partial payment can be marked as Paid or Unpaid.
The Invoice will show as Partial on the Invoices page:
Details about the outstanding amount will be shown in the Totals when viewing the Invoice:
Refunded:
You can refund a partial or the full amount by clicking on Action > Refund while viewing a Paid Invoice.
Unpaid:
An Unpaid Invoice is visible to the client. It can be marked as Paid, Cancelled, marked as Uncollectable or Deleted.