My mobile app is too long for the screen?

Hey there. I am new with the app and erverything is going well, but I am kind of confused with one thing.

When I preview, build and test my app, I seem to have a long mobile page. In fact, it’s in 360X960 (WxH).
This would not be much of a problem if it looked okay, but when I look at my page in testing/preview mode, I don’t see the whole page and I have to scroll to see the end of the page.

This is problematic because if I build my whole app on this size, users will always need to scroll to see the bottom of the page !

If you know something about this please enlighten me haha, thanks