Remember to apply this only if it is still not written on build.prop. You can experiment with these.
What you need to have is the root explorer app which you can download on apps page. Also you will need to have a rooted galaxy y phone. ALWAYS MAKE A BACKUP COPY!
- open root explorer
- go to system/apps
- change r/w to r/o
- long press on build.prop and open in text editor
- add the needed lines below
- reboot phone
to check the tweaks.