Every time you initiate Rambox, it will automatically check for updates. If there is one, the app will start downloading the update in the background as long as the "Automatically download updates" option is enabled.
When finished downloading the update, the app will ask you with a banner or in the About Rambox window to restart Rambox.
You can also check for updates manually by clicking in the Menu -> Help -> About Rambox.
Here we find the "Check now" button, which is used to check for updates manually.
Also, there is the "Automatically download updates" option, to check for updates every time you open Rambox and then, every 4 hours.
Finally, we find the "Stable channel/Beta channel" menu. By choosing the "Beta channel" option, you take part in our beta program, and will be able to see and test our upcoming new features and bug fixes before the stable version goes public.
You can learn more about the beta program in the following LINK.