When a user account is disabled soon after changing the password, this might be caused by saved passwords in browsers, e-mail-programs or the wifi access profiles on computers or smartphones. These programs or apps may use the saved (old) passwords for automatic login attempts in the background - which always fail and lead to many wrong login attempts at the user account. For security reasons, a user account is temporarily disabled, when too many wrong login attempts are detected in a short time.
In this case all these programs and apps have to be updated to the new password, or the programs and apps should be setup to not use the password save function.
After some waiting time, the user account is re-enabled and the user is able to login again.