(edited by Chuo.4238)
Targeting System Broken
Yes it’s very frustrating, nothing worse than targetting a non-threatening (yellow) target way off to the side of the screen when half a dozen angry mobs are trying to rip your face off.
It’s just bugged to hell and the priorities for targetting are not right.
The issue you are experiencing is frustrating. It most likely is due to the mouse right-clicking as you describe. For some reason, Anet allowed the right mouse button to be used as a targeting method, which is different from Guild Wars 1. I can only suggest to try and use the right mouse button as your targeting mechanism. I retrained myself to do just that. It is difficult to use the mouse like this since the right mouse button also is how you have to turn the character point of view. After awhile you will get used to it. Hopefully, the right click targeting feature will be toggable in a future update so those of us that want to turn it off can do so.