All of the transaction number starts from 0001 by default. However, you can set your own running sequence number by enable the steps follow below:
1. Go to My Biztory from the top menu bar then click on Sales Tab.
2. Scroll down to enable Custom Transaction No. and fill in the number you wanted to start from in Next Sales Ref Num field.
(Example: If the number set as 1001, that means the next sales invoice will be numbered INV1001.)