How to stop other users seeing my files?

I've just found out that the another user on my shared Mac can see all of my files and folders.

I am set up as an admin on the machine - the other user is set up with a named account with no admin rights.

They have shown me that they can access all of my folders and files including documents, pictures and music.

When I check under my profile, the folders are set to read and write access for me, and "no access" for "everyone". I've also tried setting individual files to these settings but they can still be seen by the other user account.

A couple of other things I've noticed:

1. although the other non admin user account is named, it shows up as "visitor" when looking at the file structure.

2. There is a home icon by my username - my account is shown under "users".

3. The permissions on the home folder are set to "no access" to everyone but me.

Can anyone advise how I go about securing my own user account? I've always been very confident on Mac security and have been quite surprised / concerned about the apparent lack of security on my own computer.

Many thanks.