Hi emmanuelazzopard,
Thanks for posting. Can we try to use other browser and and see if it still shows the invoices and quotations mixed up? We can also look at the Audit log to check if there were manual changes made on the transactions that may cause the mix up. You may click on the gear icon on top right > Tools > Audit Log.
For further assistance, we'd highly suggest you contacting our QuickBooks Online Support via Chat or Phone Support Hotline on this link: https://help.quickbooks.intuit.com/en_AU/contact. This way, you can do screenshare with our live support team so they can check further on your transactions.