creating a rectangle

Can't believe I have to ask this, but I've found myself in quite a strange predicament. I don't know since when, but atleast in my version of photoshop when creating a rectangle, without pressing any keys, it scales from the center.  Weird, but in itself not a huge deal.

The problem is that no other key allows me to scale from corner to corner. Especially weird because my countrys adobe site says that pressing the alt key scales the shape from the center and without any key presses, it scales from corner to corner. 

Even stranger still, pressing the alt key whilst in the shape tool opens up the color picker. Only after creating one rectangle pressing the alt key opens up some kind of negative boolean function that, miraculously, does scale from corner to corner. 

I checked the shortcuts, color picker has only one shortcut assigned to it in my set-up: i.

So I have no idea what to do, can't believe making a rectangle can be so confusing