Word 2011 for Mac. Can't save changes, I have to always 'save as' a different file.

[yoshinaria]

I have a Macbook pro 10.6.8.
Whenever I edit my word document, I have to save as a new document in order to save the changes. What do I need to do to just click 'save' to save the changes? I need your help!

 

[Titillating]

Is there any kind of error message coming up that is preventing you from simply saving it? Never heard of anything like this.