How can i cook brie in my oven without it turning into like, butter.?!

You're cooking it too long.

Brie is very soft to begin with. It only needs to be heated through until it's soft enough to spread.

I've often used brie in this recipe: you take a sheet of puff pastry, and put it on a baking tray, then slice a small brie (not thin slices) and put the slices on the puff pastry, and bake for about 20 mins at about 200 Celsius. It's just soft and golden brown, while the pastry is done.

I think your oven is set too hot - try 375 F or gas mark 5, and if that's still too hot, lower it even more.

There is a baked brie recipe where a whole brie is wrapped in dough and cooked in an oven.
If I were you and you wanted to put it on bread then put it in the oven, I would but the broiler on and let it heat from the top only till just melted and no longer. Not sure I'm understanding your question though...

Brie is pretty soft cheese and cooking it for any length of time at those kinds of temps will yield very soft buttery cheese.
What exactly are you trying to do with it?
It might be that a different type of cheese is better for baking what ever you are attempting.