Q: I want to change the invoice code format. For example, for the company ABCD, instead of the format I-ABCD0001, I want to have the following format:

ABCD-20-0001

(Client code)-(Year)-(Invoice number).

How do I do that?

A: Unfortunately, the format of the client-specific codes is fixed and can't be altered.
You can alter, to a degree, the format of the global invoice codes.

Go to "Advanced Settings/Administrator >> Codes" and enter "YY-" into the "prefix" field. Remove everything from the suffix field (note that the program will ignore the prefix when soring by global code).

In the invoice template, replace \INVOICE_CODE\ with \CLIENT_CODE\-\INVOICE_GLOBAL_CODE\