How to stop microsoft word opening old documents

Recently when I open a word document on my mac, multiple previously opened word documents also open. All of these documents that open are ones which I have opened from the emails in the mail part of the desktop.

Currently 6 previous documents open. When I quit word after this has happened gives an error message and send report to microsoft usual notice.

I have already went into general settings and selected the 'close windows when quitting an app' button and changed the recent items to none with no luck.

Is there any way to stop this happening as is very frustrating and so far I have not found an answer

Thanks,

Phil