Sync - not copy - documents from OneDrive
When you add a OneDrive document today in Teams this document is saved as a local copy in Teams, i.e. any changes in the original document will not appear in the Teams document since it is not syncing with the original document. Please enable sync from the original document!!
As it is now, if you add the same document to several channels and you want to make a change in this document you will have to change it in all channels, which is very time consuming.