I’ve just noticed that when you convert any Quote to Invoice, the default Terms and Footers defined in Settings > Company details > Defaults are not being converted from Quote Terms to Invoice Terms and from Quote Footer to Invoice Footer, which creates a great confusion as a result.
Currently, the newly generated Invoices still contain its Quote’s content (e.g. “In case you accept the Terms of this Quote, please proceed with the payment before the due date”), which don’t apply for the Invoices (that are already paid), etc.