Tree size problem when using terrain tool

This is probably an easy question to answer. My tree must be thin and with a medium size, when I created it, it looked a little bit different to this, (fat and small) but I changed the scale of it in the "transform" window from my tree, and it looked perfect!, so I went to my terrain, press on the "place trees" button and I started placing them on big scale... But they all look fat and small again!, it's weird, because when I drag my tree from the project directly to the terrain it looks as I have adjusted it (thin and medium size). Anyone knows how to place them on big amounts with the "place trees" tool, but without changing the scale that I have adjusted on the tree? Please reply!