I think you don't need to download the stylus chrome extension to reveal the hidden features you can do it manually by following this guide
https://bitcointalk.org/index.php?topic=2690140.0 But all matter is the control of the voltage! so where is it?
There's no voltage control if you do this method I think you can try to check this thread
https://bitcointalk.org/index.php?topic=4425212.0 and edit the set_miner_conf.cgi find the line with voltage then you can edit the value whatever you like.
Just curious - What does "Beeper Ringing" do?
According to some article about antminer s7 it's a beep sound so if you uncheck the "beeper ringing" it might remove the beep sound of the miner.