Roles

I am somewhat confused on roles, a performed numerous searches that do not address my question. If this is a repeat, please forgive me.

I have a multisite installation, and want authors to only be able to post and edit there own stuff – so far so good.

I want editors to be able to post and manipulate author posts (to me downhill permissions).

I don’t want editors to be able to manipulate administrators posts, which seems to be the case right now (to me uphill permission).

I would think the hiearchy would be top down, with no lower up.

Am I missing something?

Thanks in advance!!

Ron