[Question] Am I doing something wrong while changing my strings?

I’ve been playing guitar for years now, and while I’ve gotten pretty good at the “playing” part, I still seem to struggle with the other parts of having an instrument like maintenance, setup, even string changes. I’m not the handiest.

So I recently got a PRS Custom 24. Absolutely LOVE this guitar. It came to me fully set up, and I could spend all day long doing Gilmour style double bends and it stayed perfectly in tune. Nothing I did pulled it out of tune, from fast metal thrashing to big bends, I felt like I could throw it down the stairs and it would stay in tune. Then I changed my strings. Now I play on it for just a short time and it goes off, forget about bending.

Playing those Gilmour bends is proof enough to me that the problem isn’t the guitar, it is either the strings or more likely it’s me. I have no idea what was on the guitar when I got it, but I put on D’Addario XL light. I put through the tuning peg, wind it a full turn around, and cut the ends. I tried stretching the strings as I see advised, maybe a bit better but still it isn’t like it was when I got it. What could I be doing wrong here? How can I get it back to holding tune like it was at first?