Pitch does control speed.
Power does control rate of climb or descent.
Some instructors will elect to teach it the other way around, and this does seem to work as well for instrument approaches in particular.
The reality is that they are inexplicably tied to each other because power also has a pitch effect, and pitching also creates a rate of climb or descent. In the vast majority of aeroplanes increased power causes a pitch-up and a reduction in trim speed, whilst a reduction in power causes a pitch-down and a consequent increase in trim speed.
So:
Correct approach angle / too slow = pitch down + more power
Correct approach angle / too fast = pitch up + less power
Correct speed / too high = reduce power + pitch down
Correct speed / too low = increase power + pitch up.
(And at the current stage in your training = if both are wrong, probably go around and try again next time; if feeling braver AND there's plenty of height to play with, sort out airspeed first, then flightpath).
G