How to force authors to 'submit for review'?

So currently when authors add a post they can publish it straight away.

How can i change it so that all their posts need to be reviewed first?

I've seen a few codes that can solve that but when it comes to editing an already published post, it publishes straight away and doesnt get submitted for revision.

The problem i'm having is that a user can write a post and i can review it and make sure its something aceptable and innoccent. But when i confirm it they can then change it to whatever they like without me knowing.

So far searched high and wide and seen no fix.

Any help or point into the right direction would greatly be apreciated.