incorrect form

yesterday i did a video of my sprint, i have to improve a lot my tecnique, in the start i’m improving a little bit, but i noticed two issue.
the first in the start, It seems i have my gluteus too back.
the second, i think it cause a lot of my problem between 40 to 100 m is that I put my front leg too forward…i think to explain, i see a run of some sprinter, and when they put the feet in the ground, they have the leg at the level of the head (approx) while I put my feet to far from my leg.
how can i improve this? i must do more A skip and do not do B skip?
or what?
if you don’t understand what i mean i try to put some image or video