First thing is to make sure there aren't any medical reasons for the runny bums - there are some organisms that can cause it which they can be tested for (if you do a search in the health forum you'll find some [lots!!] of threads on runny bums).
How old are the boys and what are they currently being fed on? Usually it's recommended to keep them on whatever the breeder has had them on and then wean them onto something new slowly if you want to. Quite a few of us have also had success with introducing some raw food into the diet - there are companies who sell it ready prepared for pets. But, the first thing is to rule out anything medical.
Welcome to the forum by the way
![Laughing :lol:](./images/smilies/icon_lol.gif)