I saw this post in bugs but wanted to make sure the suggestion made it here. Please update the UI hotbar so that spells that have multiple levels maybe have a unique border and that when you select the spell it gives you some kind of option to select the level of the spell you want to cast. Right now you have multiple icons to represent the multiple spell levels instead of 1 icon that gives you an option to select a different level for the cast. Would help minimize the use/clutter of hotbar slots and cycling through the hotbar and potentially reduce some confusion as I'm seeing some players not understand that if they want to cast at 2nd level they need to add the 2nd level spell icon to the hotbar.
Just to clarify, if I press the magic missile icon it should pop up with the levels the spell can be cast at for me to choose. Maybe the icon should show a unique mark on it to indicate it has multiple cast options.