How to set up the Invoice # (prefix)

Step 1  
Company – User config
Step 2  
Select the user.

Step 3  
Change the status (true) the Current setting for “OrderCustomReqNumber” by clicking the edit option and the click “Ok”

Step 4  
Add the Prefix Number or letters on the “OrderCustomReqNumberPrefix” example (JS) by clicking the edit option and the click “OK”

Video.

https://youtu.be/14UB3a338IY