The Invoice Sequence can be changed at the beginning of the financial year or at the beginning of the day for Sales, Refund and Advance order.
This configuration can be set by going to Settings -> Sales Configurations screen and set the Reset sale/Refund sequence configuration value as one of the below.
Never - The invoice sequence number will not be reset at all at any time
At day end - The invoice sequence number will be reset at the beginning of each day to the value set in starting sequence number for each register.
Note: This is a global configuration which will be effective for all the Registers across the locations.
Note: By default it will be set as "April", you can change the month as per your country (if you want to change the invoice sequence during Year begin)
Note: In order to change the invoice sequence, please make sure that there is no open session for the Register.