everything on email is ok except when connecting with thunderbird password is incorrect is telling but i have created correctly the password on user accounts.
no one can help you with such little information. Can you add more, background, pictures, the requested information about Virtualmin, things like that,
reading the mail log file would be a good start, without looking at error logs no one will have any idea as to what is wrong.
you need to look at the mail log at the time you try to log in with thunderbird so you can see what is going wrong, if you don’t understand the log entries copy & paste them here