From the beginning I have a few keys on a Macbook Air and a Pro Macbook 2015 that are slightly tilted (uneven, not level) with the majority of the keyboard.

What's the best way to fix these? Lift and hold them by the corner? Press hard to reset the springs? Pop the key off and put it back in? Must call AppleCare (really, is there another way)? Some other technique?

Also, how would you fix a tilted key on a 2015 rMB?

[Spheric Harlot]

I don't think tilted keys are likely to happen on a retina MacBook.

On the others: the scissor mechanism can be replaced. It's slightly involved, and I wouldn't do it myself.