Microsoft Word - Not opening to full-window size

Hi everyone,

When opening a new document, rather than word opening to full screen windowed (not actually full screen, but maximised without going to full screen where I can still see the dock) instead it opens to only a quarter of my screen size. I keep changing this and it doesn't update for the next time I use the application. Please see attachments below to gain an understanding of which I mean.

Anyone have any ideas as to how I can resolve this?

Thank you!