How to change default document behavior

There is a workaround for this.  When you are in teams right click the 3 dots next to General and click "open in sharepoint"

When in Sharepoint online click on the gear next to your picture or initials (in the top right of the screen)

Click on Library settings

Select Advanced Settings in General Settings

In "Opening Documents in the Browser" Change to Open in the client application

Go back to the documents in Sharepoint online and copy and paste the entire web address

Go Back to Teams

Right Click Documents Library and select Remove

Select the plus and select website

Name it whatever you like

Paste the document library web address you just copied

Select Save

It will now open the desktop app as default