Here is something they should fix. If you queue as a dps for LFR, then queue as tank for a heroic, if the LFR queue doesn't join (coz not enough heals/tanks click yes or whatever) when it requeues you it updates your role to what you have selected for heroics.
ie. If you queue as dps, do a heroic as tank, it requeues you as tank if you dont get into the first group that pops up.
... so many hours wasted.