Tap the select mode button on the top right of the screen to enter selection mode.
In selection mode,
- Tap a photo you want to select or deselect.
- Tap a date to select or deselect all photos in a date.
- Tap a month section header to select or deselect all photos in a month.
- Swipe left or right to start drag selection.
- Long press a photo, date or month to enter selection mode and select at once.
- If you long press the select mode button, the context menu appears.