Settings in Microsoft Teams

Press Control + Comma (,) to open the Settings in Microsoft Teams.
Here you can choose Dark Mode colour scheme, set up your voicemail, set files to open in Desktop apps, etc.
There are 9 categories listed down the left hand side of the Settings window. Arrow Down to the category you want and press Enter to open that section.
Then use Tab to move through the settings, Arrow keys to choose from lists and Spacebar to check boxes.
Press Escape when finished.