i have gotten over 80 on many stages buti still dont have eternal on them

have you gone back to the stage to retry them and get the menu where you choose?

You must make it into island. Talk to that animal, then, after "Yes/no" there is "Eternal/Normal"

You mean points, right? It is the final point that have to be 80 (no one can make such mistake)

After you get your first Eternal (no matter which level, it comes when you get one) , king says you about it in Prince Island.

You get only one level by one (another "can't-be-made" mistake...)