Credit note issue

I am facing a problem, I make a sales invoice, then I make credit note, showing total amount due, as below:

So what problem are you facing ?

You have not explained why you think this is a problem. Manager applied an available credit for this customer to a sales invoice. You can read about that subject here: https://guides.manager.io/10355.

I also notice that your software is several hundred updates behind. You should update. The Guides are written for the current version, and some aspects of Manager’s behavior with respect to automatic allocations have changed since your version.

Thank you very much for your advise, pls tel me how can i update the software? I hope if I update my software, hope my problem will be solve.

just download the new version and install it without uninstalling your old Manager version.

You update software exactly the same way you originally installed.

Since you did not explain what you think your problem is, it is not possible to tell whether it will be affected by newer software. I suspect it will not, because what you did show was normal behavior for the version you had. The basic behavior for handling customer credits has not changed, only some specific aspects relating to overpaid invoices.