Can't scroll through all my files - only results for 'a' or 'z'

This is very frustrating because on windows and ipad this works no problem, but on macbook I can't scroll through all my files from a to z. The scroll just goes to the bottom of screen and doesn't enable me to scroll down beyond what I think is all my 'a' files. Of course there is probably a simple solution, so thanks in advance for any help with this.

JD