brunopalermo is right, if you simply need to set different values for two variables, event groups is a huge overkill.
If you don't like his solution, just create one variable Difficulty and a function SetDifficulty:
> Function SetDifficulty
if Difficulty=1 : set life=50, lifeMax=50
else if Difficulty=2 : set life=100, lifeMax=100
else if Difficulty=3 : set life=200, lifeMax=200
When player chooses game difficulty, set the variable, write it to local storage and call this function.
On start of layout read this variable from local storage and call the function:
> On start of layout
Local storage get "difficulty"
System wait for previous action
set Difficulty=max(1, LocalStorage.ItemValue)
Call SetDifficulty()
Thanks, dop2000
I finally make it work with continue button by putting "On Load Complete" then compare difficulty level global variable and it worked.
What I am doing is quite lengthy, I will defiantly adopt what you and brunopalermo suggesting me to do in future. As always Thank you very much.