Oh dear - poor Sarah, must be very confusing if even some of our old hands on here are getting it wrong!
I agree with the the earlier post that suggest go out there and try it. Learn by actual experience and repeat until YOU understand what will happen. Plonk loco on DCC track, turn the control knob "forward". Loco will move forward. Stop the loco. Pick up loco and turn it round. turn the control knob "forward" - the loco will still go forward, in the opposite direction to what is was.
If you do the same thing on analogue DC track, the loco will run backward after you turn it round.
On DC, the direction of the controller knob influences the voltage and polarity to the track and indicates the direction a loco will go round the track (clockwise or anticlockwise). You can swap the power feed wires over and the direction will change. DC controls the track.
On DCC, the direction of the controller knob influences digital commands sent out to the loco decoder and indicates the direction the loco will move (forward or backward) relative to its "front". You can swap the power feed wires and the direction will NOT change. DCC controls the loco.
It can take a while for long time DC folk changing over to DCC to "unlearn" driving "left" or "right" from where they're standing, and to learn to drive "forward" or "backward" instead.