What happens to associated expenses when I void an invoice?

What happens to associated expenses when I void an invoice?

Hello,

I regularly use expenses or logged hours to generate invoices.

A customer has asked me to void an invoice and submit a revised version. If I void an invoice, do the associated expenses go back to the "not billed" state, or do I need to re-enter them?

If it does not return those expenses to "not billed", is there any other way to do that?

Willam Tracy