Hey guys playing on xbox one here. It might be a noob question but now I’m trying to copy top players and when it comes to my skills I have a problem. I have 3 categories corpses, reanimation and blood & bones. When I look at top players they have 3 times blood & bones. No corpses and reanimation category. I just can’t find how to do it I need help pls !
Not sure about consoles, but on pc there is an option in the gameplay menu to unbind skills so that you can select any skill from any category for any skill button. I’m sure there is such an option on console. Maybe try in the console specific forum if you can’t find it on your own.
Thank you Khord I’ve found it it’s called elective mode in the gameplay options 
Even with elective mode some skills cannot be assigned to the mouse skill slots, particularly the LMB. The game will tell you if this is an issue and black/grey out that button when trying to assign that particular skill to it.