every time, when I update my application, I automatically find it on the last page of the most popular apps. before the update it was among the first pages. it's normal? is there a way to keep my app still in the same position?
Yes, that's normal, When you update an app it's a new version and numbers are reset. When an auto-migration occurs, the same thing happens with everything that was auto-updated.
The only way to limit it is to not update your app as often.
