[CentOS] login case sensitivity

hello,

some users' login fails since they type upper
case for their user ids  ,etc ...

how can case sensitivity be disabled so they can login
with mix of upper and lower case?

this is what i tried:

in /etc/sssd/sssd.conf i tested this below

[domain/default]
case_sensitive = false


i stopped  sssd, deleted all inside /var/sss/db and
started  sssd  but that did not  help ....



thank you,
F-