use postgres as database with studio

Hi,
I'm using bonita 7.5.1 and I try to use postgres as database.
I changed the database values into file:
/home/BonitaBPMCommunity-7.5.1/workspace/tomcat/setup/database.properties.

When I start bonita using script : /home/BonitaBPMCommunity-7.5.1/workspace/tomcat/start-bonita.sh, engine is connected to postgres database.
But when I start studio with script /home/OODRIVEGROUP/s.marouani/BonitaBPMCommunity-7.5.1/BonitaBPMCommunity , engine use always h2 as database and tomcat arguments are: -Dsysprop.bonita.db.vendor=h2

I changed the database values into file:
/home/BonitaBPMCommunity-7.5.1/plugins/org.bonitasoft.studio.console.libs_7.5.1.201706021514/tomcat/setup/database.properties.
But same result.

Why there are tow tomcat?
How to use postgres as database when I start engine form studio?

Thanks!