For example, if i have altitude hold selected, if i press the trim release and fly the aircraft to a new altitude and then release, the new altitude will then be held. but some helicopters return to what the original settings were.
If the "Altitude Hold" caption is still lit, and you press the force trim and fly to a new altitude, when you release the trim, the machine will head back to the original altitude. Same with heading, if you don't turn by using the heading bug, it will go back to the bug.