As u certainly know, u can configure your spells button by World of Warcraft shortcuts but sometime, your shortcuts who have been set by WoW way is in conflict with shortcuts set by Trinity.
The best way is to configure buttons by Trinity Configuration Utility and this guide will show u how to do it.
Hello, and welcome to this tutorial to learn use Trinity Bars !
As u see, spell bars is empty, open your spells book...
...and put some spells on bars by just dragging/dropping it.
Now we have added some buttons, close spells book.
Now click on the minimap button bag next the map in the top left of your screen. It extends with some buttons inside.
Now click on the Trinity bars button as u see on the screenshot, it extends to three buttons ...
Click on the key button for Trinity pass in Key Binding Mode.
Now just Mouse Over any button of the bars and press "1" or any shortcut u need ! If it works correctly, u got a message who is saying that Button number 1 have been bound to "1".
That's it ! U got it ! Just configure your buttons with any shortcuts and when u have finished ...
Just go to the minimap buttons bag again to desactivate keu button back to key binding off mode and then back in normal to play !
Enjoy !