IDK, this is a pretty basic feature. All I could find was one mention of the hot bar in the game manual - although each sovereign had an entire 2 page lay out <.< - no info on how to set the hot bar up, etc.
Seems kind of lame to have not much info on that basic feature. In the FE scenario @ second part Relias turns in to a Mage type w/ few levels spells - first battle entered I was like WTF! totally random hot bar layout. No problem until a person can't figure out how to move freakin buttons around 
w/o asking on the forums...
