Presets acting very strangely

It's been a while since I used camera raw, but i noticed mine had updated recently. 

I go in and start playing with presets and I just can't make any sense of how they work. 

So...there's a long list of them 

- Adaptive: portrait

- Adaptive: sky etc. 

I hover over one and see the histogram change, hover over another and see it change again. Move back to teh previous once and its diferent again. 

Like it seems to apply its effects totally at random so presets have totally random impacts on the picture. And if I click two am I adding two? There's nothing in the UI to indicate that X preset has been applied or that I can, I don't know, take it off maybe. 

It's incredibly confusing what on earth they're doing. Whcih is a shame because some of them are really nice, but it appears to be an absolute pain to get them to do something predictably. What am I missing?