Mine two are not that tame either. They are both about a year old. When we moved to a new house I put masking tape up in squares on the large windows in their room for five days and that seemed to do the trick. I only lock mine in their cage at night as Caleb has had the odd night terror so he is safest in a closed cage. The rest of the time I let them free all day. I have budgie secured this new place so I don't have to worry leaving them out, they won't get hurt.
But in the old flat they each flew in to each of the two windows once. And then they never did that again. They didn't appear to get hurt, perhaps it only hurt them a little bit.