To edit or add an IBAN to your company, go to Settings > Company info.
Under Bank details, you can update your IBAN or add an extra one by clicking on +Add IBAN/BIC.
Tip:
if you create outgoing invoices on the platform, don't forget to go to your Settings > Outbound > Create online, then add your updated IBAN in the IBAN field. Doing this will display your updated IBAN properly on your outgoing invoices.