In Genie you have the option to use the large or small clinical window. To adjust which window you use, simply navigate to File > User Preferences > General and either tick or untick the Use Large Clinical Window option. You can also toggle the Open Clinical window to Notes Page preference to dictate the information you see by default when opening the window.
For minor changes in the layout of the window, you can click and drag the dividers between certain columns and areas. When you hover your mouse cursor over such a divider - for example, the divider between the preview area and the rest of the window, or the dividers between the columns in the list of attachments - the pointer will change to a double-ended arrow that indicates this can be adjusted. Click and drag using this pointer, and you will be able to resize various areas of the window to suit your needs.