Properties.. when they are read and used?

Hello,
In my test , I have a user define variable named USERS, who's value is ${__property(nusers)}.
In the thread group, I set number of threads to USERS.
In user.properties, I set nusers to 10.

When I run Jmeter from the command line, the number of threads is correctly read from the user.properties file.
I can also change nusers on the command line and it works fine.

WHen I run the test from the gui, it runs with 50 users. Jmeter does not appear to read the value from user.properties.

1. Where is it getting the 50 from?
2. Should the property be read from the user.properties file?

Thank you.