Password issue, RT 3.8.6

Hi folks

I am new to RT world, gearing up(purchasing book).

Until I get up to speed I have two problems but I am a novice.

RT users are continually complaining about the RT password.

After I change their password on the RT GUI, they use it once then

The password fails and USER ask me to change it again, they say this has
been a problem for some

Time. I have created new user and attempted login, it works first time
but after that it fails.

Can anyone provide troubleshooting steps for this process?

Next RT USERS complain when creating a ticket, and complete the CC
field, the users in the CC field

Aren’t emailed. How can I troubleshoot this using processing versus
filling out the ticket and

Seeing if the email is CC’d?

I apologize for basic questions finding my bearings.