How to get slower: LCD goes back to the initial display too early...

Hi,
I use Full Graphic Smart Controller.

When I set Z axis with using Full Graphic Smart Controller,
the display goes back to the initial display in a few seconds.

So, I have to do the same operation from "Z axis moving" to "initial display" over and over
before I start printing.

Please tell me where I overwrite Marlin firmware.

I hope that this isn't too late to be of use. The timeout that returns the menu to the initial page is set with the LCD_TIMEOUT_TO_STATUS variable in the ultralcd.h file. This is on line 66 of the latest RC bugfix version (and probably very near there on other versions). It is to set to 15000 milliseconds by default.