Welcome. My understanding is that the visualiser should be placed where the tissue responds to the air the best. We want to move the location / angle of the visualizer such that the air moves through and interacts with the tissue the most unobstructed. This ensures optimal efficiency or at least removes any poor setup to start with.
I would tend to go with your instinct–if you feel that you get more resonance / a more sympathetic vibration with the bell lower towards the floor, then go with that. But be careful you’re not manipulating / rolling your bottom lip under your top lip too much rather than reducing the aperture size by bringing the aperture corners inwwards horizontally from the sides towards the air column / center of the MP.
That’s my understanding, FWIW.
I too play with my bell lower towards the floor and find that’s most natural for me and provides the best resonance / efficiency. However, I have to be careful not to revert to old habits of rolling the bottom lip under my top lip / clamping / manipulating.