First, don't test games using Safari. Use any other browser on an iPhone. I don't know what the problem is, but the issue is unrelated to Alpha, Beta, Gamma.
Second, I also started my C3 journey with a desire to build apps using Alpha, Beta, Gamma. The orientation features work great, it just takes a little time to learn how.
To start learning to work with the orientation begin with the Infinite jumping template: editor.construct.net
Just use the template as the base of your game until you get the feel of how it works. Then you can move on to making games from scratch.
Third, when testing, Lock your phone into the portrait or landscape. If your game is made for landscape, lock your phone into landscape, same if the game is made for portrait. When you actually make the app, you won't need to do that, but while you are testing, using a browser, you need to lock your phone to portrait or landscape for a good test. (If your phone doesn't have that option, there are apps that will)
Hope that helps.