Whenever the desktop app is updated, you will not have to do anything (the app updates automatically). At the top right of Teams, you will find a menu that allows you to access Settings and More, alongside your profile picture, and then select Check for updates if you wish to monitor for updates.
There is always an up-to-date version of the web app available. There is just something about it that is good in that way.
The Teams mobile app can be downloaded and installed from the Apple App Store or the Google Play Store if you are interested in updating the app.
Frequently Asked Questions
Why is Microsoft teams not updating?
When new updates to Microsoft Teams are released, the client will usually automatically update if it is installed in the Program Files directory (for example, if it is installed using installation scripts from a third party), rather than the default location of where it should be installed. There will be no updates for Microsoft Teams unless the team is idle at the time.