Hi
Eating poop is quite normal for puppies as being the youngest they generally get to eat last in the group and sometimes it may be all they get to eat. If they are hungry at least eating poop makes them feel full even if it's not giving much nutritional benefit. It is survival strategy. Of course most don't have to worry in todays world but it would have been an important survival strategy many many years ago.
Then of course most owners go "eughhhhh stop it" and start making a fuss. The pup may then think "ooh that got a reaction I'll do it again next time". For some dogs any reaction even a negative reponse is better than none and thus keep on eating it just for the attention they receive from their owners. Therefore, it's a good idea to distract pup with something else more tasty and jolly them along past and not to make it a huge issue. They do tend to grow out of it if you do this. But make a fuss and they quickly learn a way of making you jump up and down and to control your actions. Keep worming up to date and don't panic.
Rosie Barclay