It really depends on the settings on each computer.

most public computers in libraries say to be sure to log off to make sure your info is cleared.


If her/ or any computer has an administrative profile, that she uses as her main use - or that anyone can use , with no password ... that's asking for trouble.
the administrator account can access all accounts on the computer.

I have 5 profile accounts on my computer and I am the only admin account. everyone logs on to their own profile.
and logs off when done.

she should turn on the guest account or even set up a limited use account that will have limited uses on the computer if she is letting others use it.
Sharing your computer ?
Consider making other user accounts or profiles on your shared computer-
http://neurotalk.psychcentral.com/post243586-10.html