When firstly accessing the editing features, you can choose between a default or simple mode

Simple mode

Is intended for lightweight editing and adjustments. It covers basic options including whitebalance, Exposure, Contrast, Shadows and Highlights, Clarity, Sharpness and Noise Reduction.

This mode is recommended for Smartphones, smaller tablets or for users who just want to do quick edits.

Default mode

Extends the simple mode by offering Whitebalance presets (raw images only), Layer-Based adjustments (Gradient, Circular, Brush, Lasso), Lens-Corrections and Effects

Since the default mode has a lot of options and sliders, it's recommended to use on tablets or devices with larger screen size (at least 7")

Changing modes

You can always switch your mode, even while editing your images. Go to Menu -> Edit Mode