Invoices for an account can be created automatically or manually.
This setting, as well as more options, can be set general in the financial tab of the settings section.
These settings are copied into a new account on account creation.
In the account settings, you can divert from these copied invoice settings. These settings can be found in the financial tab of the account settings pop-up.
If you choose to invoice manually, you can do this from the account screen, or for more or all accounts from the invoice settings of the financial section.
You can choose to create a proforma invoice to first check the invoice, and only after you proofed the invoice(s).
NB: Once you accepted \ finalized an invoice this invoice cannot be rolled back!
A pdf will be generated for both a proforma and final invoice.
If you want to adapt your company settings, account settings (like the address or email) etc you can always choose to regenerate the invoice with the new settings, by selecting regenerate.
To find accounts with nonstandard settings you can use the report