The slide freq bar is frustrating as it only does 5 mhz increments. Not good when blades sweet spot is 838. --freq=838 does not override the slide bar on save. You have to:
nano /var/www/minera/conf/miner_conf.json
and fix by hand.
I am not a big fan of the slide bar either. Much preferred the input box to enter frequencies. But it is no real big deal for me. I found my sweet spot for the Blades so I doubt I will be making any further adjustments. The Minis I am still tweaking so the input box would be of value as opposed to the slider bar .
Happy Minera Mining!!!