I basically just forgot the word, I've got really vague recollection of it, I think it's SMOOTH, like I smooth my hair back But I only remember one of the example sentences in my app, I don't really believe the word I've forgotten is Smooth as the example sentence given is strange.. Can you give some words which have similar meaning? (IT'S NOT STROKE EITHER LOL) Especially it means to smooth back one's hair.
The word you are looking for is probably slick:
Definition of slick back/down
to pull (hair) back and make it look smooth or shiny by using water or some wet substance (such as hair gel)
He climbed out of the pool and slicked back his hair.
He had long sideburns and dark slicked-back hair.
You actually can use the word "smooth" in the context, just in a slightly different way:
He smoothed his hair with his hand
One can also comb their hair with their fingers, run their hands through their hair, or, for especially wild hair, tame their hair.