It depends on the app you want to update below is a guide on this 

Torrent clients can not be updated we have locked them to the most stable version (if you have ssh on your plan you are welcome to update these yourself but if it breaks the client or your seedbox you will need to repair this or format we offer no support or advice for custom changes)

App's like Plex you just need to click the Update button on your main dash it will pull the newest updates for your OS  and plex 

App's Like Sonarr, Radarr, Prowlarr, Sab etc you can update within the app under the update tab ( Make sure to make a backup of the app first you can do this within the app if the update fails or breaks the app you just reinstall it and use your backup to restore)

Some other app;s have a Update button on the app tile you can use this and as long as there is a version that is stable and tested it will update your app for you

And last some app's do not have update buttons and will not update via the main update button this will be due to them being locked to there current version either due to the updates having issues or causing  conflicts with other app's, When we have tested and made sure the update does not cause issues we will add it to the main update button ( Once again your more then welcome to try to update via ssh but we will offer no  support or advice if this breaks something )