Launch two separate excel windows

I have been trying to view two separate spread sheets in two separate excel windows. However when I open the second spreadsheet it will automatically launch in the existing excel window. I have changed the folder options in the control setting so that each folder will open in its own window.I have also set in the View options to launch folder windows in a separate process. Do you know of any settings in excel that would enable me to view the spreadsheets in separate windows (apart from the “Arrange Window” options). Also both files are quite large – could this be the problem!!! thanks