Is the RMS values of the voltage or current changed by changing the wave form? Why

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yes. For a sine wave of 100 volts peak, 200 volts P-P, the RMS is 70.7 volts

For a square wave of the same peak voltage, the RMS is 100 volts.

RMS is a measure of the area under the curve, and the square wave has more area.

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The wave form does matter becuase of the way Root Mean Squared is calculated. By squaring the mean, positive and negative amperage is accounted for. Taking the square root then resets the magnitude. Please look at the source below.

If you change the waveform then you change the RMS value.
For sinusoidal wave it is 0.7071 peak value.
For square wave = peak value.
For saw tooth = 0.578 peak value.
Rectified or stepped waves I don't have time to explain here.