Yup, You need to change direction, first a little down, then a little horizontal, and then raising up. Idea:
Sit down in a sofa or on a bed (so dropping is not an issue). Hold it in one hand and try to follow the movement with the thumb, while the other hand lifts the display up by the back edge. Then your thumb can 'feel' the movement, repeat several times, and try with both hands.
BTW, unlike traditional sliders you do not need both hands, nor do you have to push symmetrically with both hands, if you want to use two. So one can push, and one can lift the back in the other end.
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