budgie poop

I've been feeding them new things, so I'm not worried about it, but someone's poo (I never see who) is yellow and watery. They've been eating rice, pellets, raisins, hard boiled egg, peaches (and a peach juice thing I made), cucumber and millet spray. How do I get it back to the normal consistency?

I got my budgie a new friend a week ago and she's been having soft stools/diarrhea since I got her. I figured it was stress but today when cleaning their water and food bowls, the new bird (which I assume is 3-4 months old) pooped grey on my arm. It was grey and white in the center, the grey was...