I had great difficulty using the scroll bars with TheBrain Android and via the Android web browser on my Samsung Galaxy S5. I use my finger and a smartphone stylus.
However, last week I found a narrower stylus that is still designed for use on this smartphone. It is the Targus "slim stylus". It is about 75% the diameter of my initial stylus and far more precise. I can now scroll in both TheBrain Android and my Android web browser (accessing my web brain) on my Galaxy S5.
Thank you for sharing your findings. I'm glad everything is working for you now.

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