Every time I open a browser window now, it automatically goes straight to full screen, how can I change it back so that it opens up as a smaller size at first and you can then choose whether or not to make it full screen?
open a window, resize it and then close it. The next time you open it, it should be the smaller size. Then use maximise if you want it full screen. If you want it to be small again next time, click restore before you close your browser.