Khadas Forum is powered by Open-source Discourse, and following contents from Discourse you might interest:
"We’ve drastically improved the behavior of the Back button that appears on the timeline — both on desktop, and on mobile. You will see a back button pop up more reliably when you scroll up while reading a topic, so you never lose your place. And if you expand the mobile progress bar, you now have full access to the timeline, just like on desktop!"
And Discourse also support iOS and Android Apps now, take a look here for further info.