Odd, I installed it yesterday and now its not on PC. I have to blame the Windows update I ran last night, it mustn't have liked Maxthon as all I have in its folder now is a link to the forum.
I couldn't watch a video, as it wanted flash and had a link to adobe where the video should have been and it would take me to that page I linked above, so I didn't get very far at all.
What is your computer? Is it a laptop/desktop? is it a brand name or custom? Maybe I can help you with the sound part as if you have a Realtek chip on your PC, the loss of quad sound in YouTube videos appears to be a change made to the drivers and not flash itself. UP until Feb this year I could get surround though all my speakers watching YouTube but ever since I fresh installed Win 10 and removed my old Win 7 drivers, I was stuck with stereo in YouTube unless I swapped speakers from 5.1 to dual stereo