Please tell me there is another way of switching between 64mp and every other resolution than going through 6 clicks every time I want to use different camera and still be able to use my main camera full capacity.
64mp is actually worse in terms of light capture as it doesn't use pixel binning, so I'd actually say the default 16mp mode is the "full capacity" usage of the main sensor, and that's why it's the default one. 64mp is just a gimmick.
It's not a gimmick. It just needs a lot more light than 16MP plus a steady hand to show the benefit with more megapixels.