They are easy to install. Is it possible that you have mixed them up? Maybe you are using the wrong propeller or the wrong mounting plate. You cannot mix A and B mounts since they mount in the opposite direction. It is a very common mistake.
These photos might help. Torque to 6-8 in.lbs. Recommend using Loctite 222 Threadlocker and balancing the props. Do you have the ST16 controller? If you have the ST24 you probably have a H920 not the plus.