I can't su to non-root user

Question

Im in linux try to "su" to non-root user, if I try as user it's ok, but when I try su from a non-root user or ssh from anthor machine, I can't

[root@hostname]# su - userA
[userA@hostname]$

[userB@hostname]$ su - userA
Password: 
su: Authentication failure

I tried to delete user and at it again, and change the password but the problem still existed. can any one help please?

Answer 1

in my opinion that should have worked but with quick googling here's a solution https://www.tecmint.com/switch-user-account-without-password/