If you are using Teams on a mobile device, such as a smartphone or tablet, updates may happen automatically.  It will depend the settings you've made for app updates.

If you are using Teams on a computer, for example a Windows laptop or desktop, you may need to check manually for updates.  However, this is a simple process.

1. Start up Teams, if you've not already done so, and click on the account icon (either a picture or your initials) at the top right of the window.
2. Towards the bottom of the menu that appears you'll find Check for updates...  Click on this and Teams will check for updates while you continue using Teams.
3. If an update is available, Teams will install this and then prompt you to refresh the app.  You'll need to quit Teams and restart it.

Not all new features are automatically enabled in Teams.  To enable some of them, you will need to change the settings in Teams.

1. Start up Teams, if you've not already done so, and click on the account icon (either a picture or your initials) at the top right of the window.
2. Towards the top of the menu that appears you'll find Settings  Click on this and a new window appears.
3. Under Application make sure there's a tick next to Turn on new meeting experience.  If this option isn't there you've either still to update Teams or to restart.
4. Once you've ticked Turn on new meeting experience, you can close the window and then restart Teams for the change to take place.