How to Fix Phasing in Serum 2 Kicks and Basses

First I take down the phase randomization, which is the area in which Serum can randomly select a phase point. If it's at zero, every time you play a note, it will play at the same phase point.

In the graph you can see how it changes the phase. It stays in place.

If you're detuning your bass sounds, instead of detuning one oscillator, open a second oscillator, detune that one and remove the sub harmonics. This way you ensure that your first sub harmonic is not being detuned at all.

Open the splitter on mid side, add an EQ to the side and roll off the lows. This makes sure there are no lows in the side.

Alternatively, use the utility, click on mono bass and make sure the crossover frequency is around 200 to 300 hertz. That makes sure all the frequencies under that, the sub and the bass, are monophonic.