When you gain Constitution by leveling up and your mod increases do you gain past levels in health?
For example,
A gunslinger has 13 con which makes a +1 mod. If they roll 4 each level at level 4 they would have 20 health. They put their gained point into con increasing the mod to +2.
Would that effect only future levels or would you increase your health to 24?
Would it effect your current level making your health 21?