Trees are not 3D

When i paint trees they’re not 3d,they’re like an image who follows my character, although when i place them from the project explorer they’re 3d. What can i do to restore them to their 3d form?

Unity automatically billboards your trees to make them render quickly and as you get closer it swaps in the 3d models.

The field that controls this distance is called “Detail Distance” in this dialog: