Please help my Bondai

My bonsai leaves are turning yellow… please help… I’m a beginner

How do you care for it and where is it placed?

I water my plant when the soil is dry. I place under the sun once in a while.

Hello!
You don't have a spot put it on the sun permanentely?

Junipers need all the light they can get, so they don't survive for long indoors, and moving it into the sun then back in it's not good at all, changing a spot kind of makes you're tree to start adapting to that spot, and then you change it again, that can cause some stress for the plant, even because trees do not walk around xD.

Jokes aside, those two situations can lead to yellowing foliage, but keeping indoors will kill it, it would be just a matter of time.

Kokedama bonsai!! I have never seen it before. What a gimmick. It is embarasing to see what greed can make people do. 

I always tell beginners not to rush away and repot newly purshased trees. But juniper in sphagnum moss. What a terrible idea! Junipers is not epiphytic.

So here is the first time ever I suggest repotting a newly purshased tree. Gently remove as much sphagnum as possible without damaging the roots. Then plant the tree with the remaining sphagnum into a proper bonsai pot in a good quality bonsai soil. 

Oh, I didn't even noticed it was a in a kokedama, that's a first for me, I thought it was over a rock under that sphagnum or just covering the roots at first glance... xD

Yep, there it is, a new way to kill a Juniper, glad it made it here before it's too late (I think).