Am I doing something wrong ? Or can some one suggest some better folders ?
With the type of folder that you have linked, depending on how tightly the size of the coin fits the corresponding jacket, there is always the likelihood that a coin(s) will fall out if given the opportunity.
Lighthouse do provide a storage system called Numis that stops this from happening by having an inner sleeve that the coins go into which in turn slides into an outer sleeve.https://www.onlinecoinsandcollectab...album-system
The downside I find though is that the sheets aren't standard size so they don't hold as many coins and the matching albums covers for them are quite expensive. You can do though as I have done and store the sleeves in a standard 3-ring folder.