Excel jumps while booting? [View all]

Several weeks ago, as soon as I opened my desktop Mac I had a notice of a new Excel. Was going to ask whether it would still read my old files but left it.

Now, each time when I boot I am faced with a full screen Excel spreadsheet.

Do others face it? Any idea on how to disable it?

Don't get me wrong. Everything that has to do with nickels and dimes (and dollars) is entered on an Excel spreadsheet one way or the other. But this is getting tiresome.