Hi, I'm wondering if these problems can be solved without any hardware changes:

1. The touchscreen is way too sensitive after the update to the latest ROM (from Android 6 to 7). I do not actually have to touch, for it to trigger. This also causes the phone to often detect the keys next to the ones I’m pressing, or detect double-taps where there was only one tap. This drives me crazy, since makes typing pure torture!
Since this used to better, I'm thinking it can be undone.
Is there a way to control the touchscreen sensitivity? I want to turn it way down.

2. The touchscreen seems to currently only support two fingers. But I need 3 or 4, to play chords on the piano rolls of music apps (like Caustic). Is this a driver/firmware limitation (and hence solvable) or a hardware limitation (and hence not really solvable)?

3. The touchscreen is also not working underwater. Because water counts as touching, and so it constantly triggers touches everywhere. Which is quite risky, and even trying it once, it managed to move around icons on the home screen, turn off data, turn on the flashlight, and then call somebody. By itself. **hairs raising**
So what’s the point of it being watertight, if you can’t actually use it in the water? I would like to snorkel somewhere, and take photos of the animals and plants. But unless I can wipe it dry, which, you guessed it, I can’t, in the middle of the water, it won’t work.
This really needs to be solved.
Again, is this technically solvable or a hard hardware limitation?
(I'm even willing to solder and tinker, if that would be necessary. So software patches and firmware mods wouldn't even make me blink.)

1) android update was not the latest rom, the latest version today is 20171011. Try updating and perform a factory reset after that.
2) screen should support much more fingers!
3) this is a hardware limitation for all phones! but when it is completely underwater no more gost inputs should be made. Then you can use the hardware buttons for example to make photos.