I'm splitting my time between Moon+ and CoolReader. For a long time, I couldn't get Moon+ to work for me either. The key is to disable "full screen" mode when you're lucky enough to get the menu to come up. And then of course you have to _know_ which submenu "full screen" is on - I was only able to get one shot at the menu (before I disabled full screen) without having to exit and shut down moon+, so it took me a while. If you get the menu up, and can see the 'settings' option, it's the first option on the "Miscellaneous" submenu.
Hope that helps,