Opting in or out of a client beta can be done by opening the Steam Client and clicking on the Steam
button located on the menu at the top left. Once you have the menu open click on Settings
Mac users will need to choose Steam
and then Preferences
from the applications menu at the top of the screen.
If an open beta is available or you're already opted in, it will be displayed within the beta participation section of the Settings
page. To adjust your beta participation status click the Change
Once you've clicked Change
a window will appear with a drop-down menu. From the menu you'll be able to choose from the available betas. You'll also be able to opt-out of all betas by selecting the menu option.
When you've made your selection click Ok.
You'll then be required to restart Steam. Once Steam has been restarted it will begin updating.
If you chose to opt-in to a beta you'll continue to receive beta updates until the beta period is over, or until you opt-out. The changelog for beta update can be found within the announcements section of the Steam Client Beta group
, it's also a great place to leave feedback and bug reports.