Excel 2013, Windows 8.1

All of a sudden every time I have more than one excel file open ALL of the file names appear in the title bar. Even after closing all files and having just an empty excel window open the file names still are shown.

Not aware of this correlating to any updates but as they are pushed form our WSUS server it is possible.

It gets very confusing when you have 3-4 files open which I do ona regualr basis