Let me make you feel better. My DS was 5.1 when he finally got it. Yes, really. And I nearly went completely grey haired during that time. I promise they will get there. Consistency is the key I think. I tried anger, frustration, kindness, helpfulness etc but in the end a calm, consistent approach was what worked. So telling him that "I'm not happy about those accidents, wee/poo goes into the toilet not on your pants/floor/wherever"
He needed to see that I wasn't bothered (omg I was, and punched a few hard things a lot) and then he then also had a gradual (very gradual
change of heart and started to think it might be better to put the wee and poo in the right place.
I also made him clear it up. I know it sounds harsh, but after the millionth accident (ours were more poo than wee) I decided to let him have some more responsibility and he also didn't like doing it very much. Admittedly, I used to finish up afterwards but at least he'd had a go at cleaning his mess up.
One of the most frustrating things that tested my patience was the fact that I thought he was doing it to annoy me. I had to get that out of my head otherwise it was a constant battle and I wanted to eliminate the battle feel.
I reminded myself that he was only 2/3/4 even after a seemingly never ending day of changes (I think the record was 12).
Take time out sometimes, it can really get you down. Thinking about TTC #3 atm and I have to say potty training is etched in my mind as one of the most challenging aspects of my parenting career yet! Not sure I want to go back just yet....
Good luck and stay consistent, I promise it will happen. 