Hi Abbie, thanks for posting on the Community
We're sorry that your post wasn't picked up at the time of posting.
You can customise and update your invoice in QuickBooks Self-Employed by signing in on the web > Click the Invoices tab > Create new or open an existing > Click Work info on the bottom toolbar. This will open a side-panel where you can edit information.
Get back to us below if you require any further help!