If you have an Android phone with no obvious "menu" button, then open an existing file or start a new file. Then, "long press" the app switch button. The menu should then pop up from the bottom. Then, you get to the goodies. This includes playing all staffs, not just the one you are editing.
I note that some folks that give this app a bad review often have apparently not explored this menu, where many of the "Pro" features are located.