Let's start learning selection modes with selecting a single musical event.
Usually when a project is just opened the first musical event of the first voice on the first track is already selected. To choose another musical event simply tap on its area which contains noteheads, stem, flags, rest symbol, or empty placeholder. By default such selection is in Input mode. Other selection modes are Fragment mode and Interactive mode.
Input mode is indicated by a lighter highlighting color. It is purposed for adding notes and other data such as lyrics or chord diagrams to a selected position.
In this mode you can navigate between neighboring musical events by tapping Backward and Forward buttons.
Fragment mode, indicated by a more saturated highlighting color, is designed to perform actions on selected objects. This mode allows you to work with multiple musical events or bars. You can copy, cut, replace them or batch modificate their properties.
To switch to the Fragment mode from the Input mode tap again on the selection area. Tapping anywhere on the score in the Fragment mode resets selection to Input mode and selects a tapped musical event.
Interactive mode is a temporary mode used to select multiple objects. It is indicated by a saturated border and available via long press on the selected area in both Input and Fragment modes. After you release a finger it switches to Fragment mode allowing you to modify choosen elements.