Well this is the "simple" service menu and it's a limited version, so probably this is the reason why your changes are not being saved. To access the extended service menu there are (for what I know) two different approaches, both aiming at pressing in combination the buttons INFO + FACTORY. The 1st method involves using a .wav file in combination with your pc and an infrared transmitter to emulate that FACTORY button, a special button which is not present on the remote of your tv because it is intended to be used only by the assistance service; the other one instead requires you to have a smartphone with IR capabilities (like the Samsung Galaxy S4) in order to emulate that button within an app. Personally I use this second approach and it works.
You should make a search on the forum by yourself in order to better understand the details, but just to start I've put here for you some links that I've just found, which hopefully should help you:
viewtopic.php?f=75&t=7882&hilit=extende ... u&start=10 (read all the pages)
viewtopic.php?f=66&t=7974&hilit=extended+service+menu (again, read all the pages)
PS: on these pages you will also read about 3SPEED button: simply ignore it. For your purpose you only need the FACTORY and the INFO button, this last one being already on your tv remote.
