AttributeModifiers Question

I had set the "generic.maxHealth-10-Hearts" to my diamond_chestplate.

Then, i ate apple to build my Hearts to max(30-Hearts).

But, if i left the game,the next time i enter the game, i only got 20-Hearts,i need to eat many apple to let my HP to 30-Hearts.

How can i save my HP more than 20-Max-Hearts after i leave the game?