Excel on Mac - View Multiple Files at Once

I have been using MS Excel on a Mac to view csv data. I am trying to open two files at once to view them side by side. I can open any file in excel, but once I try to open another file to compare, the first one disappears.

I have tried using command + o from within an open spreadsheet. I have also opened the new file from the finder. In all cases, I can't find my previous spreadsheet once the new one is on screen.

Is it possible to view and arrange open files? Command + ` is not helping. I'm assuming my old files are open even though I can't see them. If I'm wrong, is there something I should be doing so that my previous files don't close when I open a new one?

I am mostly unfamiliar with the Mac OS UI, so this isn't the only place where I have trouble finding my application windows. As a result, please don't hold back even the most basic advice about how to use the OS as it pertains to this issue.

Edit: this issue doesn't occur when I open a new file from a non-full-screen excel window. However, I'd still like to know how this works when I am using full-screen applications.

Solution 1:

I recently had this problem, or I thought I did, in Keynote. Keynote would open new files in tabs, not a new window. It looked like my original file was gone but it was still there is a different tab. Look under the toolbar in excel and see if there is another tab open.