Engineers always know what actions are possible in their products, but users have no idea. If you want a user to use a feature of your product, you need to tell them it’s there. But don’t expect them to read a product guide or watch a tutorial, you need to make the various actions perfectly discoverable.
Do this with menu buttons, animations, color, and so on. Essentially, make buttons look like buttons; don’t hide things off-screen; don’t assume your users will swipe (add little arrow buttons or something); and so on.