On the form view of an account journal, in the first tab, there is a many2one link to the sequence. When you create a new journal, you can keep this field empty and a new sequence will be automatically created when you save the journal.

On sale and purchase journals, you have an additionnal option to have another sequence dedicated to refunds.

Upon module installation, all existing journals will be updated with a journal entry sequence (and also a credit note sequence for sale and purchase journals). You should update the configuration of the sequences to fit your needs. You can uncheck the option *Dedicated Credit Note Sequence* on existing sale and purchase journals if you don't want it. For the journals which already have journal entries, you should update the sequence configuration to avoid a discontinuity in the numbering for the next journal entry.
