This is not a How To so much as a how not to. When you copy and paste drawings between MS Office applications, they travel with all their properties and editability. Problem is, different applications behave in different ways.
Everyone knows about the time they spent 2 hours trying to make a lovely Powerpoint diagram look like not-garbage in the Word document that was already running late.
How To:
Always paste your Powerpoint diagrams etc into word as “Enhanced Metafiles”.
Edit > Paste Special… > Enhanced Metafile
This will mean they are not editable (who cares?) but are resizeable – including text. They will look exactly the same as in the Powerpoint screen (yay!) but can be resized with no loss of definition and can be otherwise treated just like a static image.