First of all, before you start, make sure the Mod wheel is at the lowest position and the pitch bend is in the middle position.

Go to Global>System>Calibrate>Wheels & AT.

Now move the pitch bend first up to the highest position, then let it snap back into the middle position. Now move it down to the lowest position. Repeat that five times. Make sure to push it all the way towards the upper and lower boundaries and don’t press or turn anything else on Quantum while you are doing it. Then move the mod wheel to the uppermost and lowermost position five times, again don’t press or turn anything else on while you are doing it

Afterwards, press more than five keys at the same time with high and low pressure to set the sensitivity for the aftertouch range.

Press Done when finished and then reboot Quantum. Now tap onto the VU meters in the lower left corner of the screen and switch to the MIDI Monitor. Check if everything works as it should. Pitch bend and mod wheel should not produce any messages unless they are being moved. If pitchbend, mod wheel and aftertouch are not working correctly, repeat the calibration process and follow the steps above exactly as mentioned.