Hi dartie! Welcome
Sorry about the bad experience! Many bonsai dealers are great people, willing to help, but there are a few bad apples in the bunch.
Even though your tree may not be in the sun at 5pm, there's more light than you would think in the shade. I'm guessing there's some reason why you don't want to leave it outside all the time-but you may want to leave it until it gets dark. If possible, leave the little bugger out all the time
. The temperature difference can cause stress... and there's always the chance of dropping the tree from moving it around (experience speaking there
).....
Not sure from here, but it sounds like it may be getting a bit much water for a juniper? Junipers like it a bit dry (but not crispy). Maybe back off the misting a bit..... Basically, if the top of the soil is damp, it doesn't need any water. Course, if you just misted it the top would be damp but the roots could still be dry.... watering is the trickiest part of bonsai. Do a search on this website (search button at top) and you'll see what I mean
.
Like Jorge said, junipers can be tricky so don't feel too bad if anything happens. Personally, I had to get more trees because when I only had a few I overwatered them as I was afraid of them drying out!
Glad to see you like your new plant
. There's a lot to explore here.........