It depends on whether your (simulated) heli has a fixed pitch (FP) or collective pitch (CP) main rotor system.
With a FP system, you change the RPM of the rotor to change your lift vector (amount of lift).
With a CP system, you change the pitch of the main rotor blades to change your lift vector with the goal of maintaining a constant RPM. As you vary the pitch to control the heli, the load on the engine/motor changes. This requires a change of power output (throttle) to work in conjunction with the pitch changes (throttle curve) in order to ideally maintain a constant RPM.

So should the RPM ( "speed" ) change ... it depends on what type of heli you have.

Realistically speaking, with a heli, all of them.

Basically speaking, you at least need to move the lift control (collective). On a MODE 2 TX, this is the LEFT stick fore/aft movement. Forward increases pitch (CP) or RPM (FP) until the blades are generating more vertical thrust than the heli's weight. When the lift vector and gravity are equal, you're hovering.

In order to control your YAW orientation ... you gotta move the rudder (LEFT stick, left/right movement, MODE 2).
In order to control the Lift Vector direction, you have to control the rotor disc plane (perpendicular to gravity). Use the cyclic control to maintain the rotor disc plane (RIGHT stick, fore/aft for pitch, left/right for roll, MODE 2).

Again, realistically, you have to manipulate (or be ready to manipulate) all the controls at the same time if necessary ... welcome to heli flight.

Good Luck,
d.tipton