I want to hide all ui elements but even by checking “Hide Viewport UI” it still shows the camera I am using on the top left, plus when I play the sequencer a menu with 3 lines shows on top of the camera. Is there anyway to remove this elements?
You can find the camera on the assets that have been placed in your scene from the outliner window on the top right, and at the left side of every element there should be an eye icon. It will be hidden once you click on that
