When a coworker shares a document in Microsoft Teams, the default file open behaviour is set to open the document inside the Teams application.
Whilst this is great for single pane of glass working, it can also get in the way of other communications within Teams during the time the file is open.
For instance, you could be reviewing a large document when someone sends you an important chat. To read and respond to that chat you must first exit the document you are reviewing. This is frustrating and time consuming.
Fortunately, you can change this behaviour by setting Teams to open documents in a browser window using Office Online versions of the Office Apps suite (Word, Excel, PowerPoint etc.).
You can do this by going to Settings, click on the ellipsis (…) in the top menu bar next to your avatar and click settings. Then click on the Files tab.
Change the always open Word, PowerPoint and Excel files in option to Browser.
Whilst this will only work for those file types, it is a good optimisation to make as these are the most common files that will need to be worked on for a significant amount of time.