Did the radio actually stay in ACRO mode or did it switch back to heli? If you just change it and then cycle power, it'll stay in heli. Make sure you have a little picture of an airplane when you turn on the radio, on the home screen.
Turn off all mixes and what not.
Make sure you go through the channel mapping and calibration. If you don't, nothing will work. Futabas go in this order
1 2 3 4
Ail, Elev, Thr, Rud
JR goes
1 2 3 4
Thr, Elev, Ail, Rud
It's no surprise that the Futaba worked without channel mapping because it's the same sequence as the default radio. The Spektrum will require you to move those things around.
-Eric