quality of windows and also installation seems to a real problem in North America. Well we lived in Europe for quite a while and I can tell you there is a difference. However, something that will help solving your problem right away is to get a Poly-Urethane foam (available in Hardware stores). You can easily apply it yourself and it will hold the whole window in place. Please use it according to manufacturer's recommendations and take care that it doesn't stick to the hands or other parts of the skin (it's like minute glue, you won't get it off any more even not with soap).
If you need better windows, contact us, we got European ones.