When Samba4 work in AD-DC mode, password policy can change with samba-tool:
Disable password expiration for the Administrator account :
samba-tool user setexpiry Administrator --noexpiry
Show domain level password options :
samba-tool domain passwordsettings show
Disable password complexity at the domain level :
samba-tool domain passwordsettings set --complexity=off
Disable password history at the domain level :
samba-tool domain passwordsettings set --history-length=0
Disable password min-age at the domain level :
samba-tool domain passwordsettings set --min-pwd-age=0
Disable password max-age at the domain level :
samba-tool domain passwordsettings set --max-pwd-age=0
Disable minimum password length at the domain level :
samba-tool domain passwordsettings set --min-pwd-length=0