I am not 100% sure what you mean. Are you trying to save the auto bed-levelling data? Are you trying to bring the nozzle closer to the bed after the BL Touch has homed (G28), is that what you mean as Z offset? Have you edited Marlin so that it knows that there is a BL Touch installed? Are you using Pronterface or Octoprint to connect to the printer? If you provide more information, we may be able to give you a solution.

I have not been around 3D printing long myself, so can appreciate your frustrations.