Actually, changing the security mode is about the only setting of the Comfast that one CAN conveniently do through its mobile interface, i.e. while connected to the extender through the phone.
Connect to the extender Wifi and open your phone's web browser.
In the browser's address bar, enter '192.168.10.1' as the URL.
The Comfast login screen should come up, do the login and wait for the following automatic scan for hotspots to complete.
When you see a list of hotspots (could also be empty, depending on where you are), go to settings by tapping the 'cog' icon in the upper right corner - select 'Advanced' from the menu that pops up.
Then select 'Security Mode Setting'.
Next screen, tap the lower one of the orange buttons so that it shows 'Enable security Mode' (that is when security is actually DISabled, which is what you want).
Log off from the interface by going of the 'cog' icon again.
Reconnect to the extender, fire up the Breeze, wait what happens...