why can't i uncheck aging?

[Hydys | It/Its]

i want to prevent my sims from aging, but the option to uncheck it is grayed out. i can't interact with it or change the sim lifespan
is there a way to make it uncheckable? or is it a side effect of using cheats

[Volcott]

You can only turn off aging from either the neighborhood view or the household view, I forget which.

[Alexandrite]

If you turn off aging you should also turn off story progression or else neighbor Sims will have lots of babies that won't ever grow up.

[Me_Three]

FYI - when you go into options from the Main Menu (before selecting a town?) a lot of in-game-options are unusable (grayed out).

In-game-options require a town (aka neighborhood) to be loaded for them to function.