Oracle Database Discussions

I am a new user of SQL Developer and I am trying to figure out where it is get it's tnsnames file. When I first connected I noticed many of my Oracle databases were not available so I figured a different tnsnames was being used. SQL*Plus and Application Desktop Integrator (ADI) can find the tnsnames file I want to use. I renamed the sqlnet.ora and tnsnames.ora files in my 2 Oracle_Homes and SQLPLUS and ADI cannot connect now (as I expected). But SQL Developer continues to work with the incorrect databases. I ran regedit to look at the registry and the Oracle_Home and tnsnames registries look as I expected it would.

Is there any additional areas to look at to determine tnsnames setups?

Can SQL Developer options be changed to point to a particular tnsnames.ora file

Thanks
Mark