Can I increase trading fees to anything?

Setting the fees higher is rather flexible, but when it comes to setting fees lower that might not be possible depending on if you are on the free version of HollaEx or an upgraded version. You can review https://www.hollaex.com/pricing for info on how low you can set the fees. If you' like to know more about how to change the user trading fees please see these docs at https://docs.hollaex.com/how-tos/operator-control-panel/tiers#fees