Changing password, password not accepted

Does this project use a security plugin that increases password security? Then you would have to see what its specifications are and adjust your password accordingly or (what I would not recommend) to deactivate the plugin in question.

Alternatively, you could also store the password directly in the database on your account. See: https://www.ads-software.com/documentation/article/reset-your-password/#through-phpmyadmin – whether the security plugin used by the project tolerates this I can not judge.

“For all of them I successfully use the same password.” Really Bad Idea. At least, “abc001”, “abc002”, etc would be better than the same one.