Step 1: From your Dashboard, click on your name on the top right-hand side corner, and click on Settings.

Step 2: On your Settings tab, select the right-hand side Settings button, to go to your Agency backend settings.

Step 3: On the left-hand side select the Invoices, Offer and Payments menu, then click the Invoices sub-menu.

Step 4: turn on the Use Custom Invoice Id Sequences toggle. Once you have added the Prefix, use the Save button to save the sequence.

Each new invoice you generate will automatically follow the sequential order, increasing by +1 (e.g., if the last invoice was 001, the next will be 002, then 003, etc.).