My WordPress password for admin account is changing automatically

Do you use elementor?
It could be this:

“The critical-severity flaw is tracked as CVE-2023-32243 and impacts Essential Addons for Elementor versions 5.4.0 to 5.7.1, allowing unauthenticated attackers to arbitrarily reset the passwords of administrator accounts and assume control of the websites.”
https://www.bleepingcomputer.com/news/security/hackers-target-vulnerable-wordpress-elementor-plugin-after-poc-released/amp